diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index 49434e80abab4..e2d31162127c9 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -2592,7 +2592,7 @@ namespace ts {
         }
 
         // Currently, we only support generators that were originally async function bodies.
-        if (asteriskToken && node.emitFlags & NodeEmitFlags.AsyncFunctionBody) {
+        if (asteriskToken && getEmitFlags(node) & EmitFlags.AsyncFunctionBody) {
             transformFlags |= TransformFlags.AssertGenerator;
         }
 
@@ -2667,7 +2667,7 @@ namespace ts {
             // down-level generator.
             // Currently we do not support transforming any other generator fucntions
             // down level.
-            if (asteriskToken && node.emitFlags & NodeEmitFlags.AsyncFunctionBody) {
+            if (asteriskToken && getEmitFlags(node) & EmitFlags.AsyncFunctionBody) {
                 transformFlags |= TransformFlags.AssertGenerator;
             }
         }
@@ -2698,7 +2698,7 @@ namespace ts {
         // down-level generator.
         // Currently we do not support transforming any other generator fucntions
         // down level.
-        if (asteriskToken && node.emitFlags & NodeEmitFlags.AsyncFunctionBody) {
+        if (asteriskToken && getEmitFlags(node) & EmitFlags.AsyncFunctionBody) {
             transformFlags |= TransformFlags.AssertGenerator;
         }
 
diff --git a/src/compiler/comments.ts b/src/compiler/comments.ts
index 1bca13a4bdbc6..116a8e849a373 100644
--- a/src/compiler/comments.ts
+++ b/src/compiler/comments.ts
@@ -5,7 +5,7 @@ namespace ts {
     export interface CommentWriter {
         reset(): void;
         setSourceFile(sourceFile: SourceFile): void;
-        emitNodeWithComments(node: Node, emitCallback: (node: Node) => void): void;
+        emitNodeWithComments(emitContext: EmitContext, node: Node, emitCallback: (emitContext: EmitContext, node: Node) => void): void;
         emitBodyWithDetachedComments(node: Node, detachedRange: TextRange, emitCallback: (node: Node) => void): void;
         emitTrailingCommentsOfPosition(pos: number): void;
     }
@@ -34,22 +34,24 @@ namespace ts {
             emitTrailingCommentsOfPosition,
         };
 
-        function emitNodeWithComments(node: Node, emitCallback: (node: Node) => void) {
+        function emitNodeWithComments(emitContext: EmitContext, node: Node, emitCallback: (emitContext: EmitContext, node: Node) => void) {
             if (disabled) {
-                emitCallback(node);
+                emitCallback(emitContext, node);
                 return;
             }
 
             if (node) {
-                const { pos, end } = node.commentRange || node;
-                const emitFlags = node.emitFlags;
+                const { pos, end } = getCommentRange(node);
+                const emitFlags = getEmitFlags(node);
                 if ((pos < 0 && end < 0) || (pos === end)) {
                     // Both pos and end are synthesized, so just emit the node without comments.
-                    if (emitFlags & NodeEmitFlags.NoNestedComments) {
-                        disableCommentsAndEmit(node, emitCallback);
+                    if (emitFlags & EmitFlags.NoNestedComments) {
+                        disabled = true;
+                        emitCallback(emitContext, node);
+                        disabled = false;
                     }
                     else {
-                        emitCallback(node);
+                        emitCallback(emitContext, node);
                     }
                 }
                 else {
@@ -58,8 +60,8 @@ namespace ts {
                     }
 
                     const isEmittedNode = node.kind !== SyntaxKind.NotEmittedStatement;
-                    const skipLeadingComments = pos < 0 || (emitFlags & NodeEmitFlags.NoLeadingComments) !== 0;
-                    const skipTrailingComments = end < 0 || (emitFlags & NodeEmitFlags.NoTrailingComments) !== 0;
+                    const skipLeadingComments = pos < 0 || (emitFlags & EmitFlags.NoLeadingComments) !== 0;
+                    const skipTrailingComments = end < 0 || (emitFlags & EmitFlags.NoTrailingComments) !== 0;
 
                     // Emit leading comments if the position is not synthesized and the node
                     // has not opted out from emitting leading comments.
@@ -90,11 +92,13 @@ namespace ts {
                         performance.measure("commentTime", "preEmitNodeWithComment");
                     }
 
-                    if (emitFlags & NodeEmitFlags.NoNestedComments) {
-                        disableCommentsAndEmit(node, emitCallback);
+                    if (emitFlags & EmitFlags.NoNestedComments) {
+                        disabled = true;
+                        emitCallback(emitContext, node);
+                        disabled = false;
                     }
                     else {
-                        emitCallback(node);
+                        emitCallback(emitContext, node);
                     }
 
                     if (extendedDiagnostics) {
@@ -125,9 +129,9 @@ namespace ts {
             }
 
             const { pos, end } = detachedRange;
-            const emitFlags = node.emitFlags;
-            const skipLeadingComments = pos < 0 || (emitFlags & NodeEmitFlags.NoLeadingComments) !== 0;
-            const skipTrailingComments = disabled || end < 0 || (emitFlags & NodeEmitFlags.NoTrailingComments) !== 0;
+            const emitFlags = getEmitFlags(node);
+            const skipLeadingComments = pos < 0 || (emitFlags & EmitFlags.NoLeadingComments) !== 0;
+            const skipTrailingComments = disabled || end < 0 || (emitFlags & EmitFlags.NoTrailingComments) !== 0;
 
             if (!skipLeadingComments) {
                 emitDetachedCommentsAndUpdateCommentsInfo(detachedRange);
@@ -137,8 +141,10 @@ namespace ts {
                 performance.measure("commentTime", "preEmitBodyWithDetachedComments");
             }
 
-            if (emitFlags & NodeEmitFlags.NoNestedComments) {
-                disableCommentsAndEmit(node, emitCallback);
+            if (emitFlags & EmitFlags.NoNestedComments && !disabled) {
+                disabled = true;
+                emitCallback(node);
+                disabled = false;
             }
             else {
                 emitCallback(node);
@@ -284,17 +290,6 @@ namespace ts {
             detachedCommentsInfo = undefined;
         }
 
-        function disableCommentsAndEmit(node: Node, emitCallback: (node: Node) => void): void {
-            if (disabled) {
-                emitCallback(node);
-            }
-            else {
-                disabled = true;
-                emitCallback(node);
-                disabled = false;
-            }
-        }
-
         function hasDetachedComments(pos: number) {
             return detachedCommentsInfo !== undefined && lastOrUndefined(detachedCommentsInfo).nodePos === pos;
         }
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 66d967c69189f..4e1f455364201 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -840,6 +840,72 @@ namespace ts {
         };
     }
 
+    /**
+     * High-order function, creates a function that executes a function composition.
+     * For example, `chain(a, b)` is the equivalent of `x => ((a', b') => y => b'(a'(y)))(a(x), b(x))`
+     *
+     * @param args The functions to chain.
+     */
+    export function chain<T, U>(...args: ((t: T) => (u: U) => U)[]): (t: T) => (u: U) => U;
+    export function chain<T, U>(a: (t: T) => (u: U) => U, b: (t: T) => (u: U) => U, c: (t: T) => (u: U) => U, d: (t: T) => (u: U) => U, e: (t: T) => (u: U) => U): (t: T) => (u: U) => U {
+        if (e) {
+            const args: ((t: T) => (u: U) => U)[] = [];
+            for (let i = 0; i < arguments.length; i++) {
+                args[i] = arguments[i];
+            }
+
+            return t => compose(...map(args, f => f(t)));
+        }
+        else if (d) {
+            return t => compose(a(t), b(t), c(t), d(t));
+        }
+        else if (c) {
+            return t => compose(a(t), b(t), c(t));
+        }
+        else if (b) {
+            return t => compose(a(t), b(t));
+        }
+        else if (a) {
+            return t => compose(a(t));
+        }
+        else {
+            return t => u => u;
+        }
+    }
+
+    /**
+     * High-order function, composes functions. Note that functions are composed inside-out;
+     * for example, `compose(a, b)` is the equivalent of `x => b(a(x))`.
+     *
+     * @param args The functions to compose.
+     */
+    export function compose<T>(...args: ((t: T) => T)[]): (t: T) => T;
+    export function compose<T>(a: (t: T) => T, b: (t: T) => T, c: (t: T) => T, d: (t: T) => T, e: (t: T) => T): (t: T) => T {
+        if (e) {
+            const args: ((t: T) => T)[] = [];
+            for (let i = 0; i < arguments.length; i++) {
+                args[i] = arguments[i];
+            }
+
+            return t => reduceLeft<(t: T) => T, T>(args, (u, f) => f(u), t);
+        }
+        else if (d) {
+            return t => d(c(b(a(t))));
+        }
+        else if (c) {
+            return t => c(b(a(t)));
+        }
+        else if (b) {
+            return t => b(a(t));
+        }
+        else if (a) {
+            return t => a(t);
+        }
+        else {
+            return t => t;
+        }
+    }
+
     function formatStringFromArgs(text: string, args: { [index: number]: any; }, baseIndex?: number): string {
         baseIndex = baseIndex || 0;
 
@@ -1778,7 +1844,6 @@ namespace ts {
         this.transformFlags = TransformFlags.None;
         this.parent = undefined;
         this.original = undefined;
-        this.transformId = 0;
     }
 
     export let objectAllocator: ObjectAllocator = {
diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
index 90742f30c16fd..b3242e211de92 100644
--- a/src/compiler/emitter.ts
+++ b/src/compiler/emitter.ts
@@ -206,10 +206,8 @@ const _super = (function (geti, seti) {
 
         const sourceMap = createSourceMapWriter(host, writer);
         const {
-            emitStart,
-            emitEnd,
-            emitTokenStart,
-            emitTokenEnd
+            emitNodeWithSourceMap,
+            emitTokenWithSourceMap
         } = sourceMap;
 
         const comments = createCommentWriter(host, writer, sourceMap);
@@ -234,36 +232,27 @@ const _super = (function (geti, seti) {
         let isOwnFileEmit: boolean;
         let emitSkipped = false;
 
-        performance.mark("beforeTransform");
+        const sourceFiles = getSourceFilesToEmit(host, targetSourceFile);
 
         // Transform the source files
-        const transformed = transformFiles(
-            resolver,
-            host,
-            getSourceFilesToEmit(host, targetSourceFile),
-            transformers);
-
-        performance.measure("transformTime", "beforeTransform");
-
-        // Extract helpers from the result
+        performance.mark("beforeTransform");
         const {
-            getTokenSourceMapRange,
-            isSubstitutionEnabled,
-            isEmitNotificationEnabled,
-            onSubstituteNode,
-            onEmitNode
-        } = transformed;
-
-        performance.mark("beforePrint");
+            transformed,
+            emitNodeWithSubstitution,
+            emitNodeWithNotification
+        } = transformFiles(resolver, host, sourceFiles, transformers);
+        performance.measure("transformTime", "beforeTransform");
 
         // Emit each output file
-        forEachTransformedEmitFile(host, transformed.getSourceFiles(), emitFile, emitOnlyDtsFiles);
-
-        // Clean up after transformation
-        transformed.dispose();
-
+        performance.mark("beforePrint");
+        forEachTransformedEmitFile(host, transformed, emitFile, emitOnlyDtsFiles);
         performance.measure("printTime", "beforePrint");
 
+        // Clean up emit nodes on parse tree
+        for (const sourceFile of sourceFiles) {
+            disposeEmitNodes(sourceFile);
+        }
+
         return {
             emitSkipped,
             diagnostics: emitterDiagnostics.getDiagnostics(),
@@ -358,154 +347,137 @@ const _super = (function (geti, seti) {
             currentFileIdentifiers = node.identifiers;
             sourceMap.setSourceFile(node);
             comments.setSourceFile(node);
-            emitNodeWithNotification(node, emitWorker);
+            pipelineEmitWithNotification(EmitContext.SourceFile, node);
         }
 
         /**
          * Emits a node.
          */
         function emit(node: Node) {
-            emitNodeWithNotification(node, emitWithComments);
-        }
-
-
-        /**
-         * Emits a node with comments.
-         *
-         * NOTE: Do not call this method directly. It is part of the emit pipeline
-         * and should only be called indirectly from emit.
-         */
-        function emitWithComments(node: Node) {
-            emitNodeWithComments(node, emitWithSourceMap);
+            pipelineEmitWithNotification(EmitContext.Unspecified, node);
         }
 
         /**
-         * Emits a node with source maps.
-         *
-         * NOTE: Do not call this method directly. It is part of the emit pipeline
-         * and should only be called indirectly from emitWithComments.
+         * Emits an IdentifierName.
          */
-        function emitWithSourceMap(node: Node) {
-            emitNodeWithSourceMap(node, emitWorker);
-        }
-
         function emitIdentifierName(node: Identifier) {
-            if (node) {
-                emitNodeWithNotification(node, emitIdentifierNameWithComments);
-            }
-        }
-
-        function emitIdentifierNameWithComments(node: Identifier) {
-            emitNodeWithComments(node, emitWorker);
+            pipelineEmitWithNotification(EmitContext.IdentifierName, node);
         }
 
         /**
          * Emits an expression node.
          */
         function emitExpression(node: Expression) {
-            emitNodeWithNotification(node, emitExpressionWithComments);
+            pipelineEmitWithNotification(EmitContext.Expression, node);
         }
 
         /**
-         * Emits an expression with comments.
+         * Emits a node with possible notification.
          *
-         * NOTE: Do not call this method directly. It is part of the emitExpression pipeline
-         * and should only be called indirectly from emitExpression.
+         * NOTE: Do not call this method directly. It is part of the emit pipeline
+         * and should only be called from printSourceFile, emit, emitExpression, or
+         * emitIdentifierName.
          */
-        function emitExpressionWithComments(node: Expression) {
-            emitNodeWithComments(node, emitExpressionWithSourceMap);
+        function pipelineEmitWithNotification(emitContext: EmitContext, node: Node) {
+            emitNodeWithNotification(emitContext, node, pipelineEmitWithComments);
         }
 
         /**
-         * Emits an expression with source maps.
+         * Emits a node with comments.
          *
-         * NOTE: Do not call this method directly. It is part of the emitExpression pipeline
-         * and should only be called indirectly from emitExpressionWithComments.
+         * NOTE: Do not call this method directly. It is part of the emit pipeline
+         * and should only be called indirectly from pipelineEmitWithNotification.
          */
-        function emitExpressionWithSourceMap(node: Expression) {
-            emitNodeWithSourceMap(node, emitExpressionWorker);
+        function pipelineEmitWithComments(emitContext: EmitContext, node: Node) {
+            // Do not emit comments for SourceFile
+            if (emitContext === EmitContext.SourceFile) {
+                pipelineEmitWithSourceMap(emitContext, node);
+                return;
+            }
+
+            emitNodeWithComments(emitContext, node, pipelineEmitWithSourceMap);
         }
 
         /**
-         * Emits a node with emit notification if available.
+         * Emits a node with source maps.
+         *
+         * NOTE: Do not call this method directly. It is part of the emit pipeline
+         * and should only be called indirectly from pipelineEmitWithComments.
          */
-        function emitNodeWithNotification(node: Node, emitCallback: (node: Node) => void) {
-            if (node) {
-                if (isEmitNotificationEnabled(node)) {
-                    onEmitNode(node, emitCallback);
-                }
-                else {
-                    emitCallback(node);
-                }
-            }
-        }
-
-        function emitNodeWithSourceMap(node: Node, emitCallback: (node: Node) => void) {
-            if (node) {
-                emitStart(/*range*/ node, /*contextNode*/ node, shouldSkipLeadingSourceMapForNode, shouldSkipSourceMapForChildren, getSourceMapRange);
-                emitCallback(node);
-                emitEnd(/*range*/ node, /*contextNode*/ node, shouldSkipTrailingSourceMapForNode, shouldSkipSourceMapForChildren, getSourceMapRange);
+        function pipelineEmitWithSourceMap(emitContext: EmitContext, node: Node) {
+            // Do not emit source mappings for SourceFile or IdentifierName
+            if (emitContext === EmitContext.SourceFile
+                || emitContext === EmitContext.IdentifierName) {
+                pipelineEmitWithSubstitution(emitContext, node);
+                return;
             }
-        }
 
-        function getSourceMapRange(node: Node) {
-            return node.sourceMapRange || node;
+            emitNodeWithSourceMap(emitContext, node, pipelineEmitWithSubstitution);
         }
 
         /**
-         * Determines whether to skip leading comment emit for a node.
-         *
-         * We do not emit comments for NotEmittedStatement nodes or any node that has
-         * NodeEmitFlags.NoLeadingComments.
+         * Emits a node with possible substitution.
          *
-         * @param node A Node.
+         * NOTE: Do not call this method directly. It is part of the emit pipeline
+         * and should only be called indirectly from pipelineEmitWithSourceMap or
+         * pipelineEmitInUnspecifiedContext (when picking a more specific context).
          */
-        function shouldSkipLeadingCommentsForNode(node: Node) {
-            return isNotEmittedStatement(node)
-                || (node.emitFlags & NodeEmitFlags.NoLeadingComments) !== 0;
+        function pipelineEmitWithSubstitution(emitContext: EmitContext, node: Node) {
+            emitNodeWithSubstitution(emitContext, node, pipelineEmitForContext);
         }
 
         /**
-         * Determines whether to skip source map emit for the start position of a node.
-         *
-         * We do not emit source maps for NotEmittedStatement nodes or any node that
-         * has NodeEmitFlags.NoLeadingSourceMap.
+         * Emits a node.
          *
-         * @param node A Node.
+         * NOTE: Do not call this method directly. It is part of the emit pipeline
+         * and should only be called indirectly from pipelineEmitWithSubstitution.
          */
-        function shouldSkipLeadingSourceMapForNode(node: Node) {
-            return isNotEmittedStatement(node)
-                || (node.emitFlags & NodeEmitFlags.NoLeadingSourceMap) !== 0;
+        function pipelineEmitForContext(emitContext: EmitContext, node: Node): void {
+            switch (emitContext) {
+                case EmitContext.SourceFile: return pipelineEmitInSourceFileContext(node);
+                case EmitContext.IdentifierName: return pipelineEmitInIdentifierNameContext(node);
+                case EmitContext.Unspecified: return pipelineEmitInUnspecifiedContext(node);
+                case EmitContext.Expression: return pipelineEmitInExpressionContext(node);
+            }
         }
 
-
         /**
-         * Determines whether to skip source map emit for the end position of a node.
+         * Emits a node in the SourceFile EmitContext.
          *
-         * We do not emit source maps for NotEmittedStatement nodes or any node that
-         * has NodeEmitFlags.NoTrailingSourceMap.
-         *
-         * @param node A Node.
+         * NOTE: Do not call this method directly. It is part of the emit pipeline
+         * and should only be called indirectly from pipelineEmitForContext.
          */
-        function shouldSkipTrailingSourceMapForNode(node: Node) {
-            return isNotEmittedStatement(node)
-                || (node.emitFlags & NodeEmitFlags.NoTrailingSourceMap) !== 0;
+        function pipelineEmitInSourceFileContext(node: Node): void {
+            const kind = node.kind;
+            switch (kind) {
+                // Top-level nodes
+                case SyntaxKind.SourceFile:
+                    return emitSourceFile(<SourceFile>node);
+            }
         }
 
         /**
-         * Determines whether to skip source map emit for a node and its children.
+         * Emits a node in the IdentifierName EmitContext.
          *
-         * We do not emit source maps for a node that has NodeEmitFlags.NoNestedSourceMaps.
+         * NOTE: Do not call this method directly. It is part of the emit pipeline
+         * and should only be called indirectly from pipelineEmitForContext.
          */
-        function shouldSkipSourceMapForChildren(node: Node) {
-            return (node.emitFlags & NodeEmitFlags.NoNestedSourceMaps) !== 0;
-        }
-
-        function emitWorker(node: Node): void {
-            if (tryEmitSubstitute(node, emitWorker, /*isExpression*/ false)) {
-                return;
+        function pipelineEmitInIdentifierNameContext(node: Node): void {
+            const kind = node.kind;
+            switch (kind) {
+                // Identifiers
+                case SyntaxKind.Identifier:
+                    return emitIdentifier(<Identifier>node);
             }
+        }
 
+        /**
+         * Emits a node in the Unspecified EmitContext.
+         *
+         * NOTE: Do not call this method directly. It is part of the emit pipeline
+         * and should only be called indirectly from pipelineEmitForContext.
+         */
+        function pipelineEmitInUnspecifiedContext(node: Node): void {
             const kind = node.kind;
             switch (kind) {
                 // Pseudo-literals
@@ -541,7 +513,8 @@ const _super = (function (geti, seti) {
                 case SyntaxKind.StringKeyword:
                 case SyntaxKind.SymbolKeyword:
                 case SyntaxKind.GlobalKeyword:
-                    return writeTokenNode(node);
+                    writeTokenText(kind);
+                    return;
 
                 // Parse tree nodes
 
@@ -746,25 +719,24 @@ const _super = (function (geti, seti) {
                 case SyntaxKind.EnumMember:
                     return emitEnumMember(<EnumMember>node);
 
-                // Top-level nodes
-                case SyntaxKind.SourceFile:
-                    return emitSourceFile(<SourceFile>node);
-
                 // JSDoc nodes (ignored)
-
                 // Transformation nodes (ignored)
             }
 
+            // If the node is an expression, try to emit it as an expression with
+            // substitution.
             if (isExpression(node)) {
-                return emitExpressionWorker(node);
+                return pipelineEmitWithSubstitution(EmitContext.Expression, node);
             }
         }
 
-        function emitExpressionWorker(node: Node) {
-            if (tryEmitSubstitute(node, emitExpressionWorker, /*isExpression*/ true)) {
-                return;
-            }
-
+        /**
+         * Emits a node in the Expression EmitContext.
+         *
+         * NOTE: Do not call this method directly. It is part of the emit pipeline
+         * and should only be called indirectly from pipelineEmitForContext.
+         */
+        function pipelineEmitInExpressionContext(node: Node): void {
             const kind = node.kind;
             switch (kind) {
                 // Literals
@@ -786,7 +758,8 @@ const _super = (function (geti, seti) {
                 case SyntaxKind.SuperKeyword:
                 case SyntaxKind.TrueKeyword:
                 case SyntaxKind.ThisKeyword:
-                    return writeTokenNode(node);
+                    writeTokenText(kind);
+                    return;
 
                 // Expressions
                 case SyntaxKind.ArrayLiteralExpression:
@@ -888,7 +861,7 @@ const _super = (function (geti, seti) {
         //
 
         function emitIdentifier(node: Identifier) {
-            if (node.emitFlags & NodeEmitFlags.UMDDefine) {
+            if (getEmitFlags(node) & EmitFlags.UMDDefine) {
                 writeLines(umdHelper);
             }
             else {
@@ -1161,7 +1134,7 @@ const _super = (function (geti, seti) {
                 write("{}");
             }
             else {
-                const indentedFlag = node.emitFlags & NodeEmitFlags.Indented;
+                const indentedFlag = getEmitFlags(node) & EmitFlags.Indented;
                 if (indentedFlag) {
                     increaseIndent();
                 }
@@ -1177,24 +1150,22 @@ const _super = (function (geti, seti) {
         }
 
         function emitPropertyAccessExpression(node: PropertyAccessExpression) {
-            if (tryEmitConstantValue(node)) {
-                return;
-            }
-
             let indentBeforeDot = false;
             let indentAfterDot = false;
-            if (!(node.emitFlags & NodeEmitFlags.NoIndentation)) {
+            if (!(getEmitFlags(node) & EmitFlags.NoIndentation)) {
                 const dotRangeStart = node.expression.end;
                 const dotRangeEnd = skipTrivia(currentText, node.expression.end) + 1;
                 const dotToken = <Node>{ kind: SyntaxKind.DotToken, pos: dotRangeStart, end: dotRangeEnd };
                 indentBeforeDot = needsIndentation(node, node.expression, dotToken);
                 indentAfterDot = needsIndentation(node, dotToken, node.name);
             }
-            const shouldEmitDotDot = !indentBeforeDot && needsDotDotForPropertyAccess(node.expression);
 
             emitExpression(node.expression);
             increaseIndentIf(indentBeforeDot);
+
+            const shouldEmitDotDot = !indentBeforeDot && needsDotDotForPropertyAccess(node.expression);
             write(shouldEmitDotDot ? ".." : ".");
+
             increaseIndentIf(indentAfterDot);
             emit(node.name);
             decreaseIndentIf(indentBeforeDot, indentAfterDot);
@@ -1208,19 +1179,17 @@ const _super = (function (geti, seti) {
                 const text = getLiteralTextOfNode(<LiteralExpression>expression);
                 return text.indexOf(tokenToString(SyntaxKind.DotToken)) < 0;
             }
-            else {
+            else if (isPropertyAccessExpression(expression) || isElementAccessExpression(expression)) {
                 // check if constant enum value is integer
-                const constantValue = tryGetConstEnumValue(expression);
+                const constantValue = getConstantValue(expression);
                 // isFinite handles cases when constantValue is undefined
-                return isFinite(constantValue) && Math.floor(constantValue) === constantValue;
+                return isFinite(constantValue)
+                    && Math.floor(constantValue) === constantValue
+                    && compilerOptions.removeComments;
             }
         }
 
         function emitElementAccessExpression(node: ElementAccessExpression) {
-            if (tryEmitConstantValue(node)) {
-                return;
-            }
-
             emitExpression(node.expression);
             write("[");
             emitExpression(node.argumentExpression);
@@ -1426,7 +1395,7 @@ const _super = (function (geti, seti) {
         }
 
         function emitBlockStatements(node: Block) {
-            if (node.emitFlags & NodeEmitFlags.SingleLine) {
+            if (getEmitFlags(node) & EmitFlags.SingleLine) {
                 emitList(node, node.statements, ListFormat.SingleLineBlockStatements);
             }
             else {
@@ -1630,12 +1599,12 @@ const _super = (function (geti, seti) {
             const body = node.body;
             if (body) {
                 if (isBlock(body)) {
-                    const indentedFlag = node.emitFlags & NodeEmitFlags.Indented;
+                    const indentedFlag = getEmitFlags(node) & EmitFlags.Indented;
                     if (indentedFlag) {
                         increaseIndent();
                     }
 
-                    if (node.emitFlags & NodeEmitFlags.ReuseTempVariableScope) {
+                    if (getEmitFlags(node) & EmitFlags.ReuseTempVariableScope) {
                         emitSignatureHead(node);
                         emitBlockFunctionBody(node, body);
                     }
@@ -1679,7 +1648,7 @@ const _super = (function (geti, seti) {
             // * A non-synthesized body's start and end position are on different lines.
             // * Any statement in the body starts on a new line.
 
-            if (body.emitFlags & NodeEmitFlags.SingleLine) {
+            if (getEmitFlags(body) & EmitFlags.SingleLine) {
                 return true;
             }
 
@@ -1750,7 +1719,7 @@ const _super = (function (geti, seti) {
             write("class");
             emitNodeWithPrefix(" ", node.name, emitIdentifierName);
 
-            const indentedFlag = node.emitFlags & NodeEmitFlags.Indented;
+            const indentedFlag = getEmitFlags(node) & EmitFlags.Indented;
             if (indentedFlag) {
                 increaseIndent();
             }
@@ -2083,8 +2052,8 @@ const _super = (function (geti, seti) {
             // "comment1" is not considered to be leading comment for node.initializer
             // but rather a trailing comment on the previous node.
             const initializer = node.initializer;
-            if (!shouldSkipLeadingCommentsForNode(initializer)) {
-                const commentRange = initializer.commentRange || initializer;
+            if ((getEmitFlags(initializer) & EmitFlags.NoLeadingComments) === 0) {
+                const commentRange = getCommentRange(initializer);
                 emitTrailingCommentsOfPosition(commentRange.pos);
             }
 
@@ -2156,23 +2125,23 @@ const _super = (function (geti, seti) {
         }
 
         function emitHelpers(node: Node) {
-            const emitFlags = node.emitFlags;
+            const emitFlags = getEmitFlags(node);
             let helpersEmitted = false;
-            if (emitFlags & NodeEmitFlags.EmitEmitHelpers) {
+            if (emitFlags & EmitFlags.EmitEmitHelpers) {
                 helpersEmitted = emitEmitHelpers(currentSourceFile);
             }
 
-            if (emitFlags & NodeEmitFlags.EmitExportStar) {
+            if (emitFlags & EmitFlags.EmitExportStar) {
                 writeLines(exportStarHelper);
                 helpersEmitted = true;
             }
 
-            if (emitFlags & NodeEmitFlags.EmitSuperHelper) {
+            if (emitFlags & EmitFlags.EmitSuperHelper) {
                 writeLines(superHelper);
                 helpersEmitted = true;
             }
 
-            if (emitFlags & NodeEmitFlags.EmitAdvancedSuperHelper) {
+            if (emitFlags & EmitFlags.EmitAdvancedSuperHelper) {
                 writeLines(advancedSuperHelper);
                 helpersEmitted = true;
             }
@@ -2294,36 +2263,6 @@ const _super = (function (geti, seti) {
             }
         }
 
-        function tryEmitSubstitute(node: Node, emitNode: (node: Node) => void, isExpression: boolean) {
-            if (isSubstitutionEnabled(node) && (node.emitFlags & NodeEmitFlags.NoSubstitution) === 0) {
-                const substitute = onSubstituteNode(node, isExpression);
-                if (substitute !== node) {
-                    substitute.emitFlags |= NodeEmitFlags.NoSubstitution;
-                    emitNode(substitute);
-                    return true;
-                }
-            }
-
-            return false;
-        }
-
-        function tryEmitConstantValue(node: PropertyAccessExpression | ElementAccessExpression): boolean {
-            const constantValue = tryGetConstEnumValue(node);
-            if (constantValue !== undefined) {
-                write(String(constantValue));
-                if (!compilerOptions.removeComments) {
-                    const propertyName = isPropertyAccessExpression(node)
-                        ? declarationNameToString(node.name)
-                        : getTextOfNode(node.argumentExpression);
-                    write(` /* ${propertyName} */`);
-                }
-
-                return true;
-            }
-
-            return false;
-        }
-
         function emitEmbeddedStatement(node: Statement) {
             if (isBlock(node)) {
                 write(" ");
@@ -2447,7 +2386,7 @@ const _super = (function (geti, seti) {
                     }
 
                     if (shouldEmitInterveningComments) {
-                        const commentRange = child.commentRange || child;
+                        const commentRange = getCommentRange(child);
                         emitTrailingCommentsOfPosition(commentRange.pos);
                     }
                     else {
@@ -2503,31 +2442,13 @@ const _super = (function (geti, seti) {
         }
 
         function writeToken(token: SyntaxKind, pos: number, contextNode?: Node) {
-            const tokenStartPos = emitTokenStart(token, pos, contextNode, shouldSkipLeadingSourceMapForToken, getTokenSourceMapRange);
-            const tokenEndPos = writeTokenText(token, tokenStartPos);
-            return emitTokenEnd(token, tokenEndPos, contextNode, shouldSkipTrailingSourceMapForToken, getTokenSourceMapRange);
-        }
-
-        function shouldSkipLeadingSourceMapForToken(contextNode: Node) {
-            return (contextNode.emitFlags & NodeEmitFlags.NoTokenLeadingSourceMaps) !== 0;
-        }
-
-        function shouldSkipTrailingSourceMapForToken(contextNode: Node) {
-            return (contextNode.emitFlags & NodeEmitFlags.NoTokenTrailingSourceMaps) !== 0;
+            return emitTokenWithSourceMap(contextNode, token, pos, writeTokenText);
         }
 
         function writeTokenText(token: SyntaxKind, pos?: number) {
             const tokenString = tokenToString(token);
             write(tokenString);
-            return positionIsSynthesized(pos) ? -1 : pos + tokenString.length;
-        }
-
-        function writeTokenNode(node: Node) {
-            if (node) {
-                emitStart(/*range*/ node, /*contextNode*/ node, shouldSkipLeadingSourceMapForNode, shouldSkipSourceMapForChildren, getSourceMapRange);
-                writeTokenText(node.kind);
-                emitEnd(/*range*/ node, /*contextNode*/ node, shouldSkipTrailingSourceMapForNode, shouldSkipSourceMapForChildren, getSourceMapRange);
-            }
+            return pos < 0 ? pos : pos + tokenString.length;
         }
 
         function increaseIndentIf(value: boolean, valueToWriteWhenNotIndenting?: string) {
@@ -2692,16 +2613,6 @@ const _super = (function (geti, seti) {
             return getLiteralText(node, currentSourceFile, languageVersion);
         }
 
-        function tryGetConstEnumValue(node: Node): number {
-            if (compilerOptions.isolatedModules) {
-                return undefined;
-            }
-
-            return isPropertyAccessExpression(node) || isElementAccessExpression(node)
-                ? resolver.getConstantValue(<PropertyAccessExpression | ElementAccessExpression>node)
-                : undefined;
-        }
-
         function isSingleLineEmptyBlock(block: Block) {
             return !block.multiLine
                 && block.statements.length === 0
diff --git a/src/compiler/factory.ts b/src/compiler/factory.ts
index 48296145dbc11..d873c3ef87777 100644
--- a/src/compiler/factory.ts
+++ b/src/compiler/factory.ts
@@ -76,7 +76,7 @@ namespace ts {
         // the original node. We also need to exclude specific properties and only include own-
         // properties (to skip members already defined on the shared prototype).
         const clone = <T>createNode(node.kind, /*location*/ undefined, node.flags);
-        clone.original = node;
+        setOriginalNode(clone, node);
 
         for (const key in node) {
             if (clone.hasOwnProperty(key) || !node.hasOwnProperty(key)) {
@@ -435,7 +435,7 @@ namespace ts {
     export function createPropertyAccess(expression: Expression, name: string | Identifier, location?: TextRange, flags?: NodeFlags) {
         const node = <PropertyAccessExpression>createNode(SyntaxKind.PropertyAccessExpression, location, flags);
         node.expression = parenthesizeForAccess(expression);
-        node.emitFlags = NodeEmitFlags.NoIndentation;
+        (node.emitNode || (node.emitNode = {})).flags |= EmitFlags.NoIndentation;
         node.name = typeof name === "string" ? createIdentifier(name) : name;
         return node;
     }
@@ -444,7 +444,7 @@ namespace ts {
         if (node.expression !== expression || node.name !== name) {
             const propertyAccess = createPropertyAccess(expression, name, /*location*/ node, node.flags);
             // Because we are updating existed propertyAccess we want to inherit its emitFlags instead of using default from createPropertyAccess
-            propertyAccess.emitFlags = node.emitFlags;
+            (propertyAccess.emitNode || (propertyAccess.emitNode = {})).flags = getEmitFlags(node);
             return updateNode(propertyAccess, node);
         }
         return node;
@@ -1551,7 +1551,7 @@ namespace ts {
         }
         else {
             const expression = isIdentifier(memberName) ? createPropertyAccess(target, memberName, location) : createElementAccess(target, memberName, location);
-            expression.emitFlags |= NodeEmitFlags.NoNestedSourceMaps;
+            (expression.emitNode || (expression.emitNode = {})).flags |= EmitFlags.NoNestedSourceMaps;
             return expression;
         }
     }
@@ -1744,7 +1744,7 @@ namespace ts {
         );
 
         // Mark this node as originally an async function
-        generatorFunc.emitFlags |= NodeEmitFlags.AsyncFunctionBody;
+        (generatorFunc.emitNode || (generatorFunc.emitNode = {})).flags |= EmitFlags.AsyncFunctionBody;
 
         return createCall(
             createHelperName(externalHelpersModuleName, "__awaiter"),
@@ -2222,7 +2222,7 @@ namespace ts {
                     target.push(startOnNewLine(createStatement(createLiteral("use strict"))));
                     foundUseStrict = true;
                 }
-                if (statement.emitFlags & NodeEmitFlags.CustomPrologue) {
+                if (getEmitFlags(statement) & EmitFlags.CustomPrologue) {
                     target.push(visitor ? visitNode(statement, visitor, isStatement) : statement);
                 }
                 else {
@@ -2643,14 +2643,178 @@ namespace ts {
     export function setOriginalNode<T extends Node>(node: T, original: Node): T {
         node.original = original;
         if (original) {
-            const { emitFlags, commentRange, sourceMapRange } = original;
-            if (emitFlags) node.emitFlags = emitFlags;
-            if (commentRange) node.commentRange = commentRange;
-            if (sourceMapRange) node.sourceMapRange = sourceMapRange;
+            const emitNode = original.emitNode;
+            if (emitNode) node.emitNode = mergeEmitNode(emitNode, node.emitNode);
         }
         return node;
     }
 
+    function mergeEmitNode(sourceEmitNode: EmitNode, destEmitNode: EmitNode) {
+        const { flags, commentRange, sourceMapRange, tokenSourceMapRanges } = sourceEmitNode;
+        if (!destEmitNode && (flags || commentRange || sourceMapRange || tokenSourceMapRanges)) destEmitNode = {};
+        if (flags) destEmitNode.flags = flags;
+        if (commentRange) destEmitNode.commentRange = commentRange;
+        if (sourceMapRange) destEmitNode.sourceMapRange = sourceMapRange;
+        if (tokenSourceMapRanges) destEmitNode.tokenSourceMapRanges = mergeTokenSourceMapRanges(tokenSourceMapRanges, destEmitNode.tokenSourceMapRanges);
+        return destEmitNode;
+    }
+
+    function mergeTokenSourceMapRanges(sourceRanges: Map<TextRange>, destRanges: Map<TextRange>) {
+        if (!destRanges) destRanges = createMap<TextRange>();
+        copyProperties(sourceRanges, destRanges);
+        return destRanges;
+    }
+
+    /**
+     * Clears any EmitNode entries from parse-tree nodes.
+     * @param sourceFile A source file.
+     */
+    export function disposeEmitNodes(sourceFile: SourceFile) {
+        // During transformation we may need to annotate a parse tree node with transient
+        // transformation properties. As parse tree nodes live longer than transformation
+        // nodes, we need to make sure we reclaim any memory allocated for custom ranges
+        // from these nodes to ensure we do not hold onto entire subtrees just for position
+        // information. We also need to reset these nodes to a pre-transformation state
+        // for incremental parsing scenarios so that we do not impact later emit.
+        sourceFile = getSourceFileOfNode(getParseTreeNode(sourceFile));
+        const emitNode = sourceFile && sourceFile.emitNode;
+        const annotatedNodes = emitNode && emitNode.annotatedNodes;
+        if (annotatedNodes) {
+            for (const node of annotatedNodes) {
+                node.emitNode = undefined;
+            }
+        }
+    }
+
+    /**
+     * Associates a node with the current transformation, initializing
+     * various transient transformation properties.
+     *
+     * @param node The node.
+     */
+    function getOrCreateEmitNode(node: Node) {
+        if (!node.emitNode) {
+            if (isParseTreeNode(node)) {
+                // To avoid holding onto transformation artifacts, we keep track of any
+                // parse tree node we are annotating. This allows us to clean them up after
+                // all transformations have completed.
+                if (node.kind === SyntaxKind.SourceFile) {
+                    return node.emitNode = { annotatedNodes: [node] };
+                }
+
+                const sourceFile = getSourceFileOfNode(node);
+                getOrCreateEmitNode(sourceFile).annotatedNodes.push(node);
+            }
+
+            node.emitNode = {};
+        }
+
+        return node.emitNode;
+    }
+
+    /**
+     * Gets flags that control emit behavior of a node.
+     *
+     * @param node The node.
+     */
+    export function getEmitFlags(node: Node) {
+        const emitNode = node.emitNode;
+        return emitNode && emitNode.flags;
+    }
+
+    /**
+     * Sets flags that control emit behavior of a node.
+     *
+     * @param node The node.
+     * @param emitFlags The NodeEmitFlags for the node.
+     */
+    export function setEmitFlags<T extends Node>(node: T, emitFlags: EmitFlags) {
+        getOrCreateEmitNode(node).flags = emitFlags;
+        return node;
+    }
+
+    /**
+     * Sets a custom text range to use when emitting source maps.
+     *
+     * @param node The node.
+     * @param range The text range.
+     */
+    export function setSourceMapRange<T extends Node>(node: T, range: TextRange) {
+        getOrCreateEmitNode(node).sourceMapRange = range;
+        return node;
+    }
+
+    /**
+     * Sets the TextRange to use for source maps for a token of a node.
+     *
+     * @param node The node.
+     * @param token The token.
+     * @param range The text range.
+     */
+    export function setTokenSourceMapRange<T extends Node>(node: T, token: SyntaxKind, range: TextRange) {
+        const emitNode = getOrCreateEmitNode(node);
+        const tokenSourceMapRanges = emitNode.tokenSourceMapRanges || (emitNode.tokenSourceMapRanges = createMap<TextRange>());
+        tokenSourceMapRanges[token] = range;
+        return node;
+    }
+
+    /**
+     * Sets a custom text range to use when emitting comments.
+     */
+    export function setCommentRange<T extends Node>(node: T, range: TextRange) {
+        getOrCreateEmitNode(node).commentRange = range;
+        return node;
+    }
+
+    /**
+     * Gets a custom text range to use when emitting comments.
+     *
+     * @param node The node.
+     */
+    export function getCommentRange(node: Node) {
+        const emitNode = node.emitNode;
+        return (emitNode && emitNode.commentRange) || node;
+    }
+
+    /**
+     * Gets a custom text range to use when emitting source maps.
+     *
+     * @param node The node.
+     */
+    export function getSourceMapRange(node: Node) {
+        const emitNode = node.emitNode;
+        return (emitNode && emitNode.sourceMapRange) || node;
+    }
+
+    /**
+     * Gets the TextRange to use for source maps for a token of a node.
+     *
+     * @param node The node.
+     * @param token The token.
+     */
+    export function getTokenSourceMapRange(node: Node, token: SyntaxKind) {
+        const emitNode = node.emitNode;
+        const tokenSourceMapRanges = emitNode && emitNode.tokenSourceMapRanges;
+        return tokenSourceMapRanges && tokenSourceMapRanges[token];
+    }
+
+    /**
+     * Gets the constant value to emit for an expression.
+     */
+    export function getConstantValue(node: PropertyAccessExpression | ElementAccessExpression) {
+        const emitNode = node.emitNode;
+        return emitNode && emitNode.constantValue;
+    }
+
+    /**
+     * Sets the constant value to emit for an expression.
+     */
+    export function setConstantValue(node: PropertyAccessExpression | ElementAccessExpression, value: number) {
+        const emitNode = getOrCreateEmitNode(node);
+        emitNode.constantValue = value;
+        return node;
+    }
+
     export function setTextRange<T extends TextRange>(node: T, location: TextRange): T {
         if (location) {
             node.pos = location.pos;
@@ -2692,7 +2856,7 @@ namespace ts {
         return undefined;
     }
 
-   /**
+    /**
      * Get the name of a target module from an import/export declaration as should be written in the emitted output.
      * The emitted output name can be different from the input if:
      *  1. The module has a /// <amd-module name="<new name>" />
diff --git a/src/compiler/sourcemap.ts b/src/compiler/sourcemap.ts
index eb369be39d777..46db5188e339c 100644
--- a/src/compiler/sourcemap.ts
+++ b/src/compiler/sourcemap.ts
@@ -18,11 +18,6 @@ namespace ts {
          */
         reset(): void;
 
-        /**
-         * Gets test data for source maps.
-         */
-        getSourceMapData(): SourceMapData;
-
         /**
          * Set the current source file.
          *
@@ -41,123 +36,23 @@ namespace ts {
         emitPos(pos: number): void;
 
         /**
-         * Emits a mapping for the start of a range.
-         *
-         * If the range's start position is synthetic (undefined or a negative value), no mapping
-         * will be created. Any trivia at the start position in the original source will be
-         * skipped.
-         *
-         * @param range The range to emit.
-         */
-        emitStart(range: TextRange): void;
-
-        /**
-         * Emits a mapping for the start of a range.
-         *
-         * If the node's start position is synthetic (undefined or a negative value), no mapping
-         * will be created. Any trivia at the start position in the original source will be
-         * skipped.
-         *
-         * @param range The range to emit.
-         * @param contextNode The node for the current range.
-         * @param ignoreNodeCallback A callback used to determine whether to skip source map
-         *        emit for the start position of this node.
-         * @param ignoreChildrenCallback A callback used to determine whether to skip source
-         *        map emit for all children of this node.
-         * @param getTextRangeCallbackCallback A callback used to get a custom source map
-         *        range for this node.
-         */
-        emitStart(range: TextRange, contextNode: Node, ignoreNodeCallback: (node: Node) => boolean, ignoreChildrenCallback: (node: Node) => boolean, getTextRangeCallbackCallback: (node: Node) => TextRange): void;
-
-        /**
-         * Emits a mapping for the end of a range.
-         *
-         * If the range's end position is synthetic (undefined or a negative value), no mapping
-         * will be created.
-         *
-         * @param range The range to emit.
-         */
-        emitEnd(range: TextRange): void;
-
-        /**
-         * Emits a mapping for the end of a range.
+         * Emits a node with possible leading and trailing source maps.
          *
-         * If the node's end position is synthetic (undefined or a negative value), no mapping
-         * will be created.
-         *
-         * @param range The range to emit.
-         * @param contextNode The node for the current range.
-         * @param ignoreNodeCallback A callback used to determine whether to skip source map
-         *        emit for the end position of this node.
-         * @param ignoreChildrenCallback A callback used to determine whether to skip source
-         *        map emit for all children of this node.
-         * @param getTextRangeCallbackCallback A callback used to get a custom source map
-         *        range for this node.
-         */
-        emitEnd(range: TextRange, contextNode: Node, ignoreNodeCallback: (node: Node) => boolean, ignoreChildrenCallback: (node: Node) => boolean, getTextRangeCallbackCallback: (node: Node) => TextRange): void;
-
-        /**
-         * Emits a mapping for the start position of a token.
-         *
-         * If the token's start position is synthetic (undefined or a negative value), no mapping
-         * will be created. Any trivia at the start position in the original source will be
-         * skipped.
-         *
-         * @param token The token to emit.
-         * @param tokenStartPos The start position of the token.
-         * @returns The start position of the token, following any trivia.
-         */
-        emitTokenStart(token: SyntaxKind, tokenStartPos: number): number;
-
-        /**
-         * Emits a mapping for the start position of a token.
-         *
-         * If the token's start position is synthetic (undefined or a negative value), no mapping
-         * will be created. Any trivia at the start position in the original source will be
-         * skipped.
-         *
-         * @param token The token to emit.
-         * @param tokenStartPos The start position of the token.
-         * @param contextNode The node containing this token.
-         * @param ignoreTokenCallback A callback used to determine whether to skip source map
-         *        emit for the start position of this token.
-         * @param getTokenTextRangeCallback A callback used to get a custom source
-         *        map range for this node.
-         * @returns The start position of the token, following any trivia.
+         * @param emitContext The current emit context
+         * @param node The node to emit.
+         * @param emitCallback The callback used to emit the node.
          */
-        emitTokenStart(token: SyntaxKind, tokenStartPos: number, contextNode: Node, ignoreTokenCallback: (node: Node, token: SyntaxKind) => boolean, getTokenTextRangeCallback: (node: Node, token: SyntaxKind) => TextRange): number;
+        emitNodeWithSourceMap(emitContext: EmitContext, node: Node, emitCallback: (emitContext: EmitContext, node: Node) => void): void;
 
         /**
-         * Emits a mapping for the end position of a token.
-         *
-         * If the token's end position is synthetic (undefined or a negative value), no mapping
-         * will be created.
+         * Emits a token of a node node with possible leading and trailing source maps.
          *
+         * @param node The node containing the token.
          * @param token The token to emit.
-         * @param tokenEndPos The end position of the token.
-         * @returns The end position of the token.
+         * @param tokenStartPos The start pos of the token.
+         * @param emitCallback The callback used to emit the token.
          */
-        emitTokenEnd(token: SyntaxKind, tokenEndPos: number): number;
-
-        /**
-         * Emits a mapping for the end position of a token.
-         *
-         * If the token's end position is synthetic (undefined or a negative value), no mapping
-         * will be created.
-         *
-         * @param token The token to emit.
-         * @param tokenEndPos The end position of the token.
-         * @param contextNode The node containing this token.
-         * @param ignoreTokenCallback A callback used to determine whether to skip source map
-         *        emit for the end position of this token.
-         * @param getTokenTextRangeCallback A callback used to get a custom source
-         *        map range for this node.
-         * @returns The end position of the token.
-         */
-        emitTokenEnd(token: SyntaxKind, tokenEndPos: number, contextNode: Node, ignoreTokenCallback: (node: Node, token: SyntaxKind) => boolean, getTokenTextRangeCallback: (node: Node, token: SyntaxKind) => TextRange): number;
-
-        /*@deprecated*/ changeEmitSourcePos(): void;
-        /*@deprecated*/ stopOverridingSpan(): void;
+        emitTokenWithSourceMap(node: Node, token: SyntaxKind, tokenStartPos: number, emitCallback: (token: SyntaxKind, tokenStartPos: number) => number): number;
 
         /**
          * Gets the text for the source map.
@@ -168,44 +63,11 @@ namespace ts {
          * Gets the SourceMappingURL for the source map.
          */
         getSourceMappingURL(): string;
-    }
-
-    export function createSourceMapWriter(host: EmitHost, writer: EmitTextWriter): SourceMapWriter {
-        const compilerOptions = host.getCompilerOptions();
-        if (compilerOptions.sourceMap || compilerOptions.inlineSourceMap) {
-            if (compilerOptions.extendedDiagnostics) {
-                return createSourceMapWriterWithExtendedDiagnostics(host, writer);
-            }
-
-            return createSourceMapWriterWorker(host, writer);
-        }
-        else {
-            return getNullSourceMapWriter();
-        }
-    }
 
-    let nullSourceMapWriter: SourceMapWriter;
-
-    export function getNullSourceMapWriter(): SourceMapWriter {
-        if (nullSourceMapWriter === undefined) {
-            nullSourceMapWriter = {
-                initialize(filePath: string, sourceMapFilePath: string, sourceFiles: SourceFile[], isBundledEmit: boolean): void { },
-                reset(): void { },
-                getSourceMapData(): SourceMapData { return undefined; },
-                setSourceFile(sourceFile: SourceFile): void { },
-                emitPos(pos: number): void { },
-                emitStart(range: TextRange, contextNode?: Node, ignoreNodeCallback?: (node: Node) => boolean, ignoreChildrenCallback?: (node: Node) => boolean, getTextRangeCallback?: (node: Node) => TextRange): void { },
-                emitEnd(range: TextRange, contextNode?: Node, ignoreNodeCallback?: (node: Node) => boolean, ignoreChildrenCallback?: (node: Node) => boolean, getTextRangeCallback?: (node: Node) => TextRange): void { },
-                emitTokenStart(token: SyntaxKind, pos: number, contextNode?: Node, ignoreTokenCallback?: (node: Node) => boolean, getTokenTextRangeCallback?: (node: Node, token: SyntaxKind) => TextRange): number { return -1; },
-                emitTokenEnd(token: SyntaxKind, end: number, contextNode?: Node, ignoreTokenCallback?: (node: Node) => boolean, getTokenTextRangeCallback?: (node: Node, token: SyntaxKind) => TextRange): number { return -1; },
-                changeEmitSourcePos(): void { },
-                stopOverridingSpan(): void { },
-                getText(): string { return undefined; },
-                getSourceMappingURL(): string { return undefined; }
-            };
-        }
-
-        return nullSourceMapWriter;
+        /**
+         * Gets test data for source maps.
+         */
+        getSourceMapData(): SourceMapData;
     }
 
     // Used for initialize lastEncodedSourceMapSpan and reset lastEncodedSourceMapSpan when updateLastEncodedAndRecordedSpans
@@ -217,14 +79,12 @@ namespace ts {
         sourceIndex: 0
     };
 
-    function createSourceMapWriterWorker(host: EmitHost, writer: EmitTextWriter): SourceMapWriter {
+    export function createSourceMapWriter(host: EmitHost, writer: EmitTextWriter): SourceMapWriter {
         const compilerOptions = host.getCompilerOptions();
         const extendedDiagnostics = compilerOptions.extendedDiagnostics;
         let currentSourceFile: SourceFile;
         let currentSourceText: string;
         let sourceMapDir: string; // The directory in which sourcemap will be
-        let stopOverridingSpan = false;
-        let modifyLastSourcePos = false;
 
         // Current source map file and its index in the sources list
         let sourceMapSourceIndex: number;
@@ -236,13 +96,7 @@ namespace ts {
 
         // Source map data
         let sourceMapData: SourceMapData;
-
-        // This keeps track of the number of times `disable` has been called without a
-        // corresponding call to `enable`. As long as this value is non-zero, mappings will not
-        // be recorded.
-        // This is primarily used to provide a better experience when debugging binding
-        // patterns and destructuring assignments for simple expressions.
-        let disableDepth: number;
+        let disabled: boolean = !(compilerOptions.sourceMap || compilerOptions.inlineSourceMap);
 
         return {
             initialize,
@@ -250,12 +104,8 @@ namespace ts {
             getSourceMapData: () => sourceMapData,
             setSourceFile,
             emitPos,
-            emitStart,
-            emitEnd,
-            emitTokenStart,
-            emitTokenEnd,
-            changeEmitSourcePos,
-            stopOverridingSpan: () => stopOverridingSpan = true,
+            emitNodeWithSourceMap,
+            emitTokenWithSourceMap,
             getText,
             getSourceMappingURL,
         };
@@ -269,13 +119,16 @@ namespace ts {
          * @param isBundledEmit A value indicating whether the generated output file is a bundle.
          */
         function initialize(filePath: string, sourceMapFilePath: string, sourceFiles: SourceFile[], isBundledEmit: boolean) {
+            if (disabled) {
+                return;
+            }
+
             if (sourceMapData) {
                 reset();
             }
 
             currentSourceFile = undefined;
             currentSourceText = undefined;
-            disableDepth = 0;
 
             // Current source map file and its index in the sources list
             sourceMapSourceIndex = -1;
@@ -338,6 +191,10 @@ namespace ts {
          * Reset the SourceMapWriter to an empty state.
          */
         function reset() {
+            if (disabled) {
+                return;
+            }
+
             currentSourceFile = undefined;
             sourceMapDir = undefined;
             sourceMapSourceIndex = undefined;
@@ -345,64 +202,6 @@ namespace ts {
             lastEncodedSourceMapSpan = undefined;
             lastEncodedNameIndex = undefined;
             sourceMapData = undefined;
-            disableDepth = 0;
-        }
-
-        /**
-         * Re-enables the recording of mappings.
-         */
-        function enable() {
-            if (disableDepth > 0) {
-                disableDepth--;
-            }
-        }
-
-        /**
-         * Disables the recording of mappings.
-         */
-        function disable() {
-            disableDepth++;
-        }
-
-        function updateLastEncodedAndRecordedSpans() {
-            if (modifyLastSourcePos) {
-                // Reset the source pos
-                modifyLastSourcePos = false;
-
-                // Change Last recorded Map with last encoded emit line and character
-                lastRecordedSourceMapSpan.emittedLine = lastEncodedSourceMapSpan.emittedLine;
-                lastRecordedSourceMapSpan.emittedColumn = lastEncodedSourceMapSpan.emittedColumn;
-
-                // Pop sourceMapDecodedMappings to remove last entry
-                sourceMapData.sourceMapDecodedMappings.pop();
-
-                // Point the lastEncodedSourceMapSpace to the previous encoded sourceMapSpan
-                // If the list is empty which indicates that we are at the beginning of the file,
-                // we have to reset it to default value (same value when we first initialize sourceMapWriter)
-                lastEncodedSourceMapSpan = sourceMapData.sourceMapDecodedMappings.length ?
-                    sourceMapData.sourceMapDecodedMappings[sourceMapData.sourceMapDecodedMappings.length - 1] :
-                    defaultLastEncodedSourceMapSpan;
-
-                // TODO: Update lastEncodedNameIndex
-                // Since we dont support this any more, lets not worry about it right now.
-                // When we start supporting nameIndex, we will get back to this
-
-                // Change the encoded source map
-                const sourceMapMappings = sourceMapData.sourceMapMappings;
-                let lenthToSet = sourceMapMappings.length - 1;
-                for (; lenthToSet >= 0; lenthToSet--) {
-                    const currentChar = sourceMapMappings.charAt(lenthToSet);
-                    if (currentChar === ",") {
-                        // Separator for the entry found
-                        break;
-                    }
-                    if (currentChar === ";" && lenthToSet !== 0 && sourceMapMappings.charAt(lenthToSet - 1) !== ";") {
-                        // Last line separator found
-                        break;
-                    }
-                }
-                sourceMapData.sourceMapMappings = sourceMapMappings.substr(0, Math.max(0, lenthToSet));
-            }
         }
 
         // Encoding for sourcemap span
@@ -459,7 +258,7 @@ namespace ts {
          * @param pos The position.
          */
         function emitPos(pos: number) {
-            if (positionIsSynthesized(pos) || disableDepth > 0) {
+            if (disabled || positionIsSynthesized(pos)) {
                 return;
             }
 
@@ -495,209 +294,89 @@ namespace ts {
                     sourceColumn: sourceLinePos.character,
                     sourceIndex: sourceMapSourceIndex
                 };
-
-                stopOverridingSpan = false;
             }
-            else if (!stopOverridingSpan) {
+            else {
                 // Take the new pos instead since there is no change in emittedLine and column since last location
                 lastRecordedSourceMapSpan.sourceLine = sourceLinePos.line;
                 lastRecordedSourceMapSpan.sourceColumn = sourceLinePos.character;
                 lastRecordedSourceMapSpan.sourceIndex = sourceMapSourceIndex;
             }
 
-            updateLastEncodedAndRecordedSpans();
-
             if (extendedDiagnostics) {
                 performance.mark("afterSourcemap");
                 performance.measure("Source Map", "beforeSourcemap", "afterSourcemap");
             }
         }
 
-        function getStartPosPastDecorators(range: TextRange) {
-            const rangeHasDecorators = !!(range as Node).decorators;
-            return skipTrivia(currentSourceText, rangeHasDecorators ? (range as Node).decorators.end : range.pos);
-        }
-
         /**
-         * Emits a mapping for the start of a range.
-         *
-         * If the range's start position is synthetic (undefined or a negative value), no mapping
-         * will be created. Any trivia at the start position in the original source will be
-         * skipped.
-         *
-         * @param range The range to emit.0
-         */
-        function emitStart(range: TextRange): void;
-        /**
-         * Emits a mapping for the start of a range.
-         *
-         * If the node's start position is synthetic (undefined or a negative value), no mapping
-         * will be created. Any trivia at the start position in the original source will be
-         * skipped.
+         * Emits a node with possible leading and trailing source maps.
          *
-         * @param range The range to emit.
-         * @param contextNode The node for the current range.
-         * @param ignoreNodeCallback A callback used to determine whether to skip source map
-         *        emit for the start position of this node.
-         * @param ignoreChildrenCallback A callback used to determine whether to skip source
-         *        map emit for all children of this node.
-         * @param getTextRangeCallbackCallback A callback used to get a custom source map
-         *        range for this node.
+         * @param node The node to emit.
+         * @param emitCallback The callback used to emit the node.
          */
-        function emitStart(range: TextRange, contextNode: Node, ignoreNodeCallback: (node: Node) => boolean, ignoreChildrenCallback: (node: Node) => boolean, getTextRangeCallback: (node: Node) => TextRange): void;
-        function emitStart(range: TextRange, contextNode?: Node, ignoreNodeCallback?: (node: Node) => boolean, ignoreChildrenCallback?: (node: Node) => boolean, getTextRangeCallback?: (node: Node) => TextRange) {
-            if (contextNode) {
-                if (!ignoreNodeCallback(contextNode)) {
-                    range = getTextRangeCallback(contextNode) || range;
-                    emitPos(getStartPosPastDecorators(range));
-                }
-
-                if (ignoreChildrenCallback(contextNode)) {
-                    disable();
-                }
-            }
-            else {
-                emitPos(getStartPosPastDecorators(range));
+        function emitNodeWithSourceMap(emitContext: EmitContext, node: Node, emitCallback: (emitContext: EmitContext, node: Node) => void) {
+            if (disabled) {
+                return emitCallback(emitContext, node);
             }
-        }
 
-        /**
-         * Emits a mapping for the end of a range.
-         *
-         * If the range's end position is synthetic (undefined or a negative value), no mapping
-         * will be created.
-         *
-         * @param range The range to emit.
-         */
-        function emitEnd(range: TextRange): void;
-        /**
-         * Emits a mapping for the end of a range.
-         *
-         * If the node's end position is synthetic (undefined or a negative value), no mapping
-         * will be created.
-         *
-         * @param range The range to emit.
-         * @param contextNode The node for the current range.
-         * @param ignoreNodeCallback A callback used to determine whether to skip source map
-         *        emit for the end position of this node.
-         * @param ignoreChildrenCallback A callback used to determine whether to skip source
-         *        map emit for all children of this node.
-         * @param getTextRangeCallbackCallback A callback used to get a custom source map
-         *        range for this node.
-         */
-        function emitEnd(range: TextRange, contextNode: Node, ignoreNodeCallback: (node: Node) => boolean, ignoreChildrenCallback: (node: Node) => boolean, getTextRangeCallback: (node: Node) => TextRange): void;
-        function emitEnd(range: TextRange, contextNode?: Node, ignoreNodeCallback?: (node: Node) => boolean, ignoreChildrenCallback?: (node: Node) => boolean, getTextRangeCallback?: (node: Node) => TextRange) {
-            if (contextNode) {
-                if (ignoreChildrenCallback(contextNode)) {
-                    enable();
-                }
+            if (node) {
+                const emitNode = node.emitNode;
+                const emitFlags = emitNode && emitNode.flags;
+                const { pos, end } = emitNode && emitNode.sourceMapRange || node;
 
-                if (!ignoreNodeCallback(contextNode)) {
-                    range = getTextRangeCallback(contextNode) || range;
-                    emitPos(range.end);
+                if (node.kind !== SyntaxKind.NotEmittedStatement
+                    && (emitFlags & EmitFlags.NoLeadingSourceMap) === 0
+                    && pos >= 0) {
+                    emitPos(skipTrivia(currentSourceText, pos));
                 }
-            }
-            else {
-                emitPos(range.end);
-            }
-
-            stopOverridingSpan = false;
-        }
 
-        /**
-         * Emits a mapping for the start position of a token.
-         *
-         * If the token's start position is synthetic (undefined or a negative value), no mapping
-         * will be created. Any trivia at the start position in the original source will be
-         * skipped.
-         *
-         * @param token The token to emit.
-         * @param tokenStartPos The start position of the token.
-         * @returns The start position of the token, following any trivia.
-         */
-        function emitTokenStart(token: SyntaxKind, tokenStartPos: number): number;
-        /**
-         * Emits a mapping for the start position of a token.
-         *
-         * If the token's start position is synthetic (undefined or a negative value), no mapping
-         * will be created. Any trivia at the start position in the original source will be
-         * skipped.
-         *
-         * @param token The token to emit.
-         * @param tokenStartPos The start position of the token.
-         * @param contextNode The node containing this token.
-         * @param ignoreTokenCallback A callback used to determine whether to skip source map
-         *        emit for the start position of this token.
-         * @param getTokenTextRangeCallback A callback used to get a custom source
-         *        map range for this node.
-         * @returns The start position of the token, following any trivia.
-         */
-        function emitTokenStart(token: SyntaxKind, tokenStartPos: number, contextNode: Node, ignoreTokenCallback: (node: Node, token: SyntaxKind) => boolean, getTokenTextRangeCallback: (node: Node, token: SyntaxKind) => TextRange): number;
-        function emitTokenStart(token: SyntaxKind, tokenStartPos: number, contextNode?: Node, ignoreTokenCallback?: (node: Node, token: SyntaxKind) => boolean, getTokenTextRangeCallback?: (node: Node, token: SyntaxKind) => TextRange): number {
-            if (contextNode) {
-                if (ignoreTokenCallback(contextNode, token)) {
-                    return skipTrivia(currentSourceText, tokenStartPos);
+                if (emitFlags & EmitFlags.NoNestedSourceMaps) {
+                    disabled = true;
+                    emitCallback(emitContext, node);
+                    disabled = false;
+                }
+                else {
+                    emitCallback(emitContext, node);
                 }
 
-                const range = getTokenTextRangeCallback(contextNode, token);
-                if (range) {
-                    tokenStartPos = range.pos;
+                if (node.kind !== SyntaxKind.NotEmittedStatement
+                    && (emitFlags & EmitFlags.NoTrailingSourceMap) === 0
+                    && end >= 0) {
+                    emitPos(end);
                 }
             }
-
-            tokenStartPos = skipTrivia(currentSourceText, tokenStartPos);
-            emitPos(tokenStartPos);
-            return tokenStartPos;
         }
 
         /**
-         * Emits a mapping for the end position of a token.
-         *
-         * If the token's end position is synthetic (undefined or a negative value), no mapping
-         * will be created.
-         *
-         * @param token The token to emit.
-         * @param tokenEndPos The end position of the token.
-         * @returns The end position of the token.
-         */
-        function emitTokenEnd(token: SyntaxKind, tokenEndPos: number): number;
-        /**
-         * Emits a mapping for the end position of a token.
-         *
-         * If the token's end position is synthetic (undefined or a negative value), no mapping
-         * will be created.
+         * Emits a token of a node with possible leading and trailing source maps.
          *
+         * @param node The node containing the token.
          * @param token The token to emit.
-         * @param tokenEndPos The end position of the token.
-         * @param contextNode The node containing this token.
-         * @param ignoreTokenCallback A callback used to determine whether to skip source map
-         *        emit for the end position of this token.
-         * @param getTokenTextRangeCallback A callback used to get a custom source
-         *        map range for this node.
-         * @returns The end position of the token.
+         * @param tokenStartPos The start pos of the token.
+         * @param emitCallback The callback used to emit the token.
          */
-        function emitTokenEnd(token: SyntaxKind, tokenEndPos: number, contextNode: Node, ignoreTokenCallback: (node: Node, token: SyntaxKind) => boolean, getTokenTextRangeCallback: (node: Node, token: SyntaxKind) => TextRange): number;
-        function emitTokenEnd(token: SyntaxKind, tokenEndPos: number, contextNode?: Node, ignoreTokenCallback?: (node: Node, token: SyntaxKind) => boolean, getTokenTextRangeCallback?: (node: Node, token: SyntaxKind) => TextRange): number {
-            if (contextNode) {
-                if (ignoreTokenCallback(contextNode, token)) {
-                    return tokenEndPos;
-                }
+        function emitTokenWithSourceMap(node: Node, token: SyntaxKind, tokenPos: number, emitCallback: (token: SyntaxKind, tokenStartPos: number) => number) {
+            if (disabled) {
+                return emitCallback(token, tokenPos);
+            }
 
-                const range = getTokenTextRangeCallback(contextNode, token);
-                if (range) {
-                    tokenEndPos = range.end;
-                }
+            const emitNode = node && node.emitNode;
+            const emitFlags = emitNode && emitNode.flags;
+            const range = emitNode && emitNode.tokenSourceMapRanges && emitNode.tokenSourceMapRanges[token];
+
+            tokenPos = skipTrivia(currentSourceText, range ? range.pos : tokenPos);
+            if ((emitFlags & EmitFlags.NoTokenLeadingSourceMaps) === 0 && tokenPos >= 0) {
+                emitPos(tokenPos);
             }
 
-            emitPos(tokenEndPos);
-            return tokenEndPos;
-        }
+            tokenPos = emitCallback(token, tokenPos);
 
+            if (range) tokenPos = range.end;
+            if ((emitFlags & EmitFlags.NoTokenTrailingSourceMaps) === 0 && tokenPos >= 0) {
+                emitPos(tokenPos);
+            }
 
-        // @deprecated
-        function changeEmitSourcePos() {
-            Debug.assert(!modifyLastSourcePos);
-            modifyLastSourcePos = true;
+            return tokenPos;
         }
 
         /**
@@ -706,6 +385,10 @@ namespace ts {
          * @param sourceFile The source file.
          */
         function setSourceFile(sourceFile: SourceFile) {
+            if (disabled) {
+                return;
+            }
+
             currentSourceFile = sourceFile;
             currentSourceText = currentSourceFile.text;
 
@@ -738,6 +421,10 @@ namespace ts {
          * Gets the text for the source map.
          */
         function getText() {
+            if (disabled) {
+                return;
+            }
+
             encodeLastRecordedSourceMapSpan();
 
             return stringify({
@@ -755,6 +442,10 @@ namespace ts {
          * Gets the SourceMappingURL for the source map.
          */
         function getSourceMappingURL() {
+            if (disabled) {
+                return;
+            }
+
             if (compilerOptions.inlineSourceMap) {
                 // Encode the sourceMap into the sourceMap url
                 const base64SourceMapText = convertToBase64(getText());
@@ -766,61 +457,6 @@ namespace ts {
         }
     }
 
-    function createSourceMapWriterWithExtendedDiagnostics(host: EmitHost, writer: EmitTextWriter): SourceMapWriter {
-        const {
-            initialize,
-            reset,
-            getSourceMapData,
-            setSourceFile,
-            emitPos,
-            emitStart,
-            emitEnd,
-            emitTokenStart,
-            emitTokenEnd,
-            changeEmitSourcePos,
-            stopOverridingSpan,
-            getText,
-            getSourceMappingURL,
-        } = createSourceMapWriterWorker(host, writer);
-        return {
-            initialize,
-            reset,
-            getSourceMapData,
-            setSourceFile,
-            emitPos(pos: number): void {
-                 performance.mark("sourcemapStart");
-                emitPos(pos);
-                performance.measure("sourceMapTime", "sourcemapStart");
-            },
-            emitStart(range: TextRange, contextNode?: Node, ignoreNodeCallback?: (node: Node) => boolean, ignoreChildrenCallback?: (node: Node) => boolean, getTextRangeCallback?: (node: Node) => TextRange): void {
-                performance.mark("emitSourcemap:emitStart");
-                emitStart(range, contextNode, ignoreNodeCallback, ignoreChildrenCallback, getTextRangeCallback);
-                performance.measure("sourceMapTime", "emitSourcemap:emitStart");
-            },
-            emitEnd(range: TextRange, contextNode?: Node, ignoreNodeCallback?: (node: Node) => boolean, ignoreChildrenCallback?: (node: Node) => boolean, getTextRangeCallback?: (node: Node) => TextRange): void {
-                performance.mark("emitSourcemap:emitEnd");
-                emitEnd(range, contextNode, ignoreNodeCallback, ignoreChildrenCallback, getTextRangeCallback);
-                performance.measure("sourceMapTime", "emitSourcemap:emitEnd");
-            },
-            emitTokenStart(token: SyntaxKind, tokenStartPos: number, contextNode?: Node, ignoreTokenCallback?: (node: Node) => boolean, getTokenTextRangeCallback?: (node: Node, token: SyntaxKind) => TextRange): number {
-                performance.mark("emitSourcemap:emitTokenStart");
-                tokenStartPos = emitTokenStart(token, tokenStartPos, contextNode, ignoreTokenCallback, getTokenTextRangeCallback);
-                performance.measure("sourceMapTime", "emitSourcemap:emitTokenStart");
-                return tokenStartPos;
-            },
-            emitTokenEnd(token: SyntaxKind, tokenEndPos: number, contextNode?: Node, ignoreTokenCallback?: (node: Node) => boolean, getTokenTextRangeCallback?: (node: Node, token: SyntaxKind) => TextRange): number {
-                performance.mark("emitSourcemap:emitTokenEnd");
-                tokenEndPos = emitTokenEnd(token, tokenEndPos, contextNode, ignoreTokenCallback, getTokenTextRangeCallback);
-                performance.measure("sourceMapTime", "emitSourcemap:emitTokenEnd");
-                return tokenEndPos;
-            },
-            changeEmitSourcePos,
-            stopOverridingSpan,
-            getText,
-            getSourceMappingURL,
-        };
-    }
-
     const base64Chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 
     function base64FormatEncode(inValue: number) {
diff --git a/src/compiler/transformer.ts b/src/compiler/transformer.ts
index 6242a2f23474c..92407af2bb9fe 100644
--- a/src/compiler/transformer.ts
+++ b/src/compiler/transformer.ts
@@ -28,46 +28,25 @@ namespace ts {
         /**
          * Gets the transformed source files.
          */
-        getSourceFiles(): SourceFile[];
+        transformed: SourceFile[];
 
         /**
-         * Gets the TextRange to use for source maps for a token of a node.
-         */
-        getTokenSourceMapRange(node: Node, token: SyntaxKind): TextRange;
-
-        /**
-         * Determines whether expression substitutions are enabled for the provided node.
-         */
-        isSubstitutionEnabled(node: Node): boolean;
-
-        /**
-         * Determines whether before/after emit notifications should be raised in the pretty
-         * printer when it emits a node.
-         */
-        isEmitNotificationEnabled(node: Node): boolean;
-
-        /**
-         * Hook used by transformers to substitute expressions just before they
-         * are emitted by the pretty printer.
+         * Emits the substitute for a node, if one is available; otherwise, emits the node.
          *
+         * @param emitContext The current emit context.
          * @param node The node to substitute.
-         * @param isExpression A value indicating whether the node is in an expression context.
+         * @param emitCallback A callback used to emit the node or its substitute.
          */
-        onSubstituteNode(node: Node, isExpression: boolean): Node;
+        emitNodeWithSubstitution(emitContext: EmitContext, node: Node, emitCallback: (emitContext: EmitContext, node: Node) => void): void;
 
         /**
-         * Hook used to allow transformers to capture state before or after
-         * the printer emits a node.
+         * Emits a node with possible notification.
          *
+         * @param emitContext The current emit context.
          * @param node The node to emit.
          * @param emitCallback A callback used to emit the node.
          */
-        onEmitNode(node: Node, emitCallback: (node: Node) => void): void;
-
-        /**
-         * Reset transient transformation properties on parse tree nodes.
-         */
-        dispose(): void;
+        emitNodeWithNotification(emitContext: EmitContext, node: Node, emitCallback: (emitContext: EmitContext, node: Node) => void): void;
     }
 
     export interface TransformationContext extends LexicalEnvironment {
@@ -75,46 +54,6 @@ namespace ts {
         getEmitResolver(): EmitResolver;
         getEmitHost(): EmitHost;
 
-        /**
-         * Gets flags used to customize later transformations or emit.
-         */
-        getNodeEmitFlags(node: Node): NodeEmitFlags;
-
-        /**
-         * Sets flags used to customize later transformations or emit.
-         */
-        setNodeEmitFlags<T extends Node>(node: T, flags: NodeEmitFlags): T;
-
-        /**
-         * Gets the TextRange to use for source maps for the node.
-         */
-        getSourceMapRange(node: Node): TextRange;
-
-        /**
-         * Sets the TextRange to use for source maps for the node.
-         */
-        setSourceMapRange<T extends Node>(node: T, range: TextRange): T;
-
-        /**
-         * Gets the TextRange to use for source maps for a token of a node.
-         */
-        getTokenSourceMapRange(node: Node, token: SyntaxKind): TextRange;
-
-        /**
-         * Sets the TextRange to use for source maps for a token of a node.
-         */
-        setTokenSourceMapRange<T extends Node>(node: T, token: SyntaxKind, range: TextRange): T;
-
-        /**
-         * Gets the TextRange to use for comments for the node.
-         */
-        getCommentRange(node: Node): TextRange;
-
-        /**
-         * Sets the TextRange to use for comments for the node.
-         */
-        setCommentRange<T extends Node>(node: T, range: TextRange): T;
-
         /**
          * Hoists a function declaration to the containing scope.
          */
@@ -139,7 +78,7 @@ namespace ts {
          * Hook used by transformers to substitute expressions just before they
          * are emitted by the pretty printer.
          */
-        onSubstituteNode?: (node: Node, isExpression: boolean) => Node;
+        onSubstituteNode?: (emitContext: EmitContext, node: Node) => Node;
 
         /**
          * Enables before/after emit notifications in the pretty printer for the provided
@@ -157,7 +96,7 @@ namespace ts {
          * Hook used to allow transformers to capture state before or after
          * the printer emits a node.
          */
-        onEmitNode?: (node: Node, emit: (node: Node) => void) => void;
+        onEmitNode?: (emitContext: EmitContext, node: Node, emitCallback: (emitContext: EmitContext, node: Node) => void) => void;
     }
 
     /* @internal */
@@ -186,14 +125,6 @@ namespace ts {
         return transformers;
     }
 
-    /**
-     * Tracks a monotonically increasing transformation id used to associate a node with a specific
-     * transformation. This ensures transient properties related to transformations can be safely
-     * stored on source tree nodes that may be reused across multiple transformations (such as
-     * with compile-on-save).
-     */
-    let nextTransformId = 1;
-
     /**
      * Transforms an array of SourceFiles by passing them through each transformer.
      *
@@ -203,18 +134,10 @@ namespace ts {
      * @param transforms An array of Transformers.
      */
     export function transformFiles(resolver: EmitResolver, host: EmitHost, sourceFiles: SourceFile[], transformers: Transformer[]): TransformationResult {
-        const transformId = nextTransformId;
-        nextTransformId++;
-
-        const tokenSourceMapRanges = createMap<TextRange>();
         const lexicalEnvironmentVariableDeclarationsStack: VariableDeclaration[][] = [];
         const lexicalEnvironmentFunctionDeclarationsStack: FunctionDeclaration[][] = [];
         const enabledSyntaxKindFeatures = new Array<SyntaxKindFeatureFlags>(SyntaxKind.Count);
-        const parseTreeNodesWithAnnotations: Node[] = [];
 
-        let lastTokenSourceMapRangeNode: Node;
-        let lastTokenSourceMapRangeToken: SyntaxKind;
-        let lastTokenSourceMapRange: TextRange;
         let lexicalEnvironmentStackOffset = 0;
         let hoistedVariableDeclarations: VariableDeclaration[];
         let hoistedFunctionDeclarations: FunctionDeclaration[];
@@ -226,22 +149,14 @@ namespace ts {
             getCompilerOptions: () => host.getCompilerOptions(),
             getEmitResolver: () => resolver,
             getEmitHost: () => host,
-            getNodeEmitFlags,
-            setNodeEmitFlags,
-            getSourceMapRange,
-            setSourceMapRange,
-            getTokenSourceMapRange,
-            setTokenSourceMapRange,
-            getCommentRange,
-            setCommentRange,
             hoistVariableDeclaration,
             hoistFunctionDeclaration,
             startLexicalEnvironment,
             endLexicalEnvironment,
-            onSubstituteNode,
+            onSubstituteNode: (emitContext, node) => node,
             enableSubstitution,
             isSubstitutionEnabled,
-            onEmitNode,
+            onEmitNode: (node, emitContext, emitCallback) => emitCallback(node, emitContext),
             enableEmitNotification,
             isEmitNotificationEnabled
         };
@@ -256,30 +171,9 @@ namespace ts {
         lexicalEnvironmentDisabled = true;
 
         return {
-            getSourceFiles: () => transformed,
-            getTokenSourceMapRange,
-            isSubstitutionEnabled,
-            isEmitNotificationEnabled,
-            onSubstituteNode: context.onSubstituteNode,
-            onEmitNode: context.onEmitNode,
-            dispose() {
-                // During transformation we may need to annotate a parse tree node with transient
-                // transformation properties. As parse tree nodes live longer than transformation
-                // nodes, we need to make sure we reclaim any memory allocated for custom ranges
-                // from these nodes to ensure we do not hold onto entire subtrees just for position
-                // information. We also need to reset these nodes to a pre-transformation state
-                // for incremental parsing scenarios so that we do not impact later emit.
-                for (const node of parseTreeNodesWithAnnotations) {
-                    if (node.transformId === transformId) {
-                        node.transformId = 0;
-                        node.emitFlags = 0;
-                        node.commentRange = undefined;
-                        node.sourceMapRange = undefined;
-                    }
-                }
-
-                parseTreeNodesWithAnnotations.length = 0;
-            }
+            transformed,
+            emitNodeWithSubstitution,
+            emitNodeWithNotification
         };
 
         /**
@@ -306,18 +200,29 @@ namespace ts {
          * Determines whether expression substitutions are enabled for the provided node.
          */
         function isSubstitutionEnabled(node: Node) {
-            return (enabledSyntaxKindFeatures[node.kind] & SyntaxKindFeatureFlags.Substitution) !== 0;
+            return (enabledSyntaxKindFeatures[node.kind] & SyntaxKindFeatureFlags.Substitution) !== 0
+                && (getEmitFlags(node) & EmitFlags.NoSubstitution) === 0;
         }
 
         /**
-         * Default hook for node substitutions.
+         * Emits a node with possible substitution.
          *
-         * @param node The node to substitute.
-         * @param isExpression A value indicating whether the node is to be used in an expression
-         *                     position.
-         */
-        function onSubstituteNode(node: Node, isExpression: boolean) {
-            return node;
+         * @param emitContext The current emit context.
+         * @param node The node to emit.
+         * @param emitCallback The callback used to emit the node or its substitute.
+         */
+        function emitNodeWithSubstitution(emitContext: EmitContext, node: Node, emitCallback: (emitContext: EmitContext, node: Node) => void) {
+            if (node) {
+                if (isSubstitutionEnabled(node)) {
+                    const substitute = context.onSubstituteNode(emitContext, node);
+                    if (substitute && substitute !== node) {
+                        emitCallback(emitContext, substitute);
+                        return;
+                    }
+                }
+
+                emitCallback(emitContext, node);
+            }
         }
 
         /**
@@ -333,154 +238,25 @@ namespace ts {
          */
         function isEmitNotificationEnabled(node: Node) {
             return (enabledSyntaxKindFeatures[node.kind] & SyntaxKindFeatureFlags.EmitNotifications) !== 0
-                || (getNodeEmitFlags(node) & NodeEmitFlags.AdviseOnEmitNode) !== 0;
+                || (getEmitFlags(node) & EmitFlags.AdviseOnEmitNode) !== 0;
         }
 
         /**
-         * Default hook for node emit.
+         * Emits a node with possible emit notification.
          *
+         * @param emitContext The current emit context.
          * @param node The node to emit.
-         * @param emit A callback used to emit the node in the printer.
+         * @param emitCallback The callback used to emit the node.
          */
-        function onEmitNode(node: Node, emit: (node: Node) => void) {
-            emit(node);
-        }
-
-        /**
-         * Associates a node with the current transformation, initializing
-         * various transient transformation properties.
-         *
-         * @param node The node.
-         */
-        function beforeSetAnnotation(node: Node) {
-            if ((node.flags & NodeFlags.Synthesized) === 0 && node.transformId !== transformId) {
-                // To avoid holding onto transformation artifacts, we keep track of any
-                // parse tree node we are annotating. This allows us to clean them up after
-                // all transformations have completed.
-                parseTreeNodesWithAnnotations.push(node);
-                node.transformId = transformId;
-            }
-        }
-
-        /**
-         * Gets flags that control emit behavior of a node.
-         *
-         * If the node does not have its own NodeEmitFlags set, the node emit flags of its
-         * original pointer are used.
-         *
-         * @param node The node.
-         */
-        function getNodeEmitFlags(node: Node) {
-            return node.emitFlags;
-        }
-
-        /**
-         * Sets flags that control emit behavior of a node.
-         *
-         * @param node The node.
-         * @param emitFlags The NodeEmitFlags for the node.
-         */
-        function setNodeEmitFlags<T extends Node>(node: T, emitFlags: NodeEmitFlags) {
-            beforeSetAnnotation(node);
-            node.emitFlags = emitFlags;
-            return node;
-        }
-
-        /**
-         * Gets a custom text range to use when emitting source maps.
-         *
-         * If a node does not have its own custom source map text range, the custom source map
-         * text range of its original pointer is used.
-         *
-         * @param node The node.
-         */
-        function getSourceMapRange(node: Node) {
-            return node.sourceMapRange || node;
-        }
-
-        /**
-         * Sets a custom text range to use when emitting source maps.
-         *
-         * @param node The node.
-         * @param range The text range.
-         */
-        function setSourceMapRange<T extends Node>(node: T, range: TextRange) {
-            beforeSetAnnotation(node);
-            node.sourceMapRange = range;
-            return node;
-        }
-
-        /**
-         * Gets the TextRange to use for source maps for a token of a node.
-         *
-         * If a node does not have its own custom source map text range for a token, the custom
-         * source map text range for the token of its original pointer is used.
-         *
-         * @param node The node.
-         * @param token The token.
-         */
-        function getTokenSourceMapRange(node: Node, token: SyntaxKind) {
-            // As a performance optimization, use the cached value of the most recent node.
-            // This helps for cases where this function is called repeatedly for the same node.
-            if (lastTokenSourceMapRangeNode === node && lastTokenSourceMapRangeToken === token) {
-                return lastTokenSourceMapRange;
-            }
-
-            // Get the custom token source map range for a node or from one of its original nodes.
-            // Custom token ranges are not stored on the node to avoid the GC burden.
-            let range: TextRange;
-            let current = node;
-            while (current) {
-                range = current.id ? tokenSourceMapRanges[current.id + "-" + token] : undefined;
-                if (range !== undefined) {
-                    break;
+        function emitNodeWithNotification(emitContext: EmitContext, node: Node, emitCallback: (emitContext: EmitContext, node: Node) => void) {
+            if (node) {
+                if (isEmitNotificationEnabled(node)) {
+                    context.onEmitNode(emitContext, node, emitCallback);
+                }
+                else {
+                    emitCallback(emitContext, node);
                 }
-
-                current = current.original;
             }
-
-            // Cache the most recently requested value.
-            lastTokenSourceMapRangeNode = node;
-            lastTokenSourceMapRangeToken = token;
-            lastTokenSourceMapRange = range;
-            return range;
-        }
-
-        /**
-         * Sets the TextRange to use for source maps for a token of a node.
-         *
-         * @param node The node.
-         * @param token The token.
-         * @param range The text range.
-         */
-        function setTokenSourceMapRange<T extends Node>(node: T, token: SyntaxKind, range: TextRange) {
-            // Cache the most recently requested value.
-            lastTokenSourceMapRangeNode = node;
-            lastTokenSourceMapRangeToken = token;
-            lastTokenSourceMapRange = range;
-            tokenSourceMapRanges[getNodeId(node) + "-" + token] = range;
-            return node;
-        }
-
-        /**
-         * Gets a custom text range to use when emitting comments.
-         *
-         * If a node does not have its own custom source map text range, the custom source map
-         * text range of its original pointer is used.
-         *
-         * @param node The node.
-         */
-        function getCommentRange(node: Node) {
-            return node.commentRange || node;
-        }
-
-        /**
-         * Sets a custom text range to use when emitting comments.
-         */
-        function setCommentRange<T extends Node>(node: T, range: TextRange) {
-            beforeSetAnnotation(node);
-            node.commentRange = range;
-            return node;
         }
 
         /**
@@ -563,70 +339,4 @@ namespace ts {
             return statements;
         }
     }
-
-    /**
-     * High-order function, creates a function that executes a function composition.
-     * For example, `chain(a, b)` is the equivalent of `x => ((a', b') => y => b'(a'(y)))(a(x), b(x))`
-     *
-     * @param args The functions to chain.
-     */
-    function chain<T, U>(...args: ((t: T) => (u: U) => U)[]): (t: T) => (u: U) => U;
-    function chain<T, U>(a: (t: T) => (u: U) => U, b: (t: T) => (u: U) => U, c: (t: T) => (u: U) => U, d: (t: T) => (u: U) => U, e: (t: T) => (u: U) => U): (t: T) => (u: U) => U {
-        if (e) {
-            const args: ((t: T) => (u: U) => U)[] = [];
-            for (let i = 0; i < arguments.length; i++) {
-                args[i] = arguments[i];
-            }
-
-            return t => compose(...map(args, f => f(t)));
-        }
-        else if (d) {
-            return t => compose(a(t), b(t), c(t), d(t));
-        }
-        else if (c) {
-            return t => compose(a(t), b(t), c(t));
-        }
-        else if (b) {
-            return t => compose(a(t), b(t));
-        }
-        else if (a) {
-            return t => compose(a(t));
-        }
-        else {
-            return t => u => u;
-        }
-    }
-
-    /**
-     * High-order function, composes functions. Note that functions are composed inside-out;
-     * for example, `compose(a, b)` is the equivalent of `x => b(a(x))`.
-     *
-     * @param args The functions to compose.
-     */
-    function compose<T>(...args: ((t: T) => T)[]): (t: T) => T;
-    function compose<T>(a: (t: T) => T, b: (t: T) => T, c: (t: T) => T, d: (t: T) => T, e: (t: T) => T): (t: T) => T {
-        if (e) {
-            const args: ((t: T) => T)[] = [];
-            for (let i = 0; i < arguments.length; i++) {
-                args[i] = arguments[i];
-            }
-
-            return t => reduceLeft<(t: T) => T, T>(args, (u, f) => f(u), t);
-        }
-        else if (d) {
-            return t => d(c(b(a(t))));
-        }
-        else if (c) {
-            return t => c(b(a(t)));
-        }
-        else if (b) {
-            return t => b(a(t));
-        }
-        else if (a) {
-            return t => a(t);
-        }
-        else {
-            return t => t;
-        }
-    }
 }
\ No newline at end of file
diff --git a/src/compiler/transformers/destructuring.ts b/src/compiler/transformers/destructuring.ts
index a66f5e21d784d..3bfa778cf9b33 100644
--- a/src/compiler/transformers/destructuring.ts
+++ b/src/compiler/transformers/destructuring.ts
@@ -66,7 +66,7 @@ namespace ts {
 
             // NOTE: this completely disables source maps, but aligns with the behavior of
             //       `emitAssignment` in the old emitter.
-            context.setNodeEmitFlags(expression, NodeEmitFlags.NoNestedSourceMaps);
+            setEmitFlags(expression, EmitFlags.NoNestedSourceMaps);
 
             aggregateTransformFlags(expression);
             expressions.push(expression);
@@ -102,7 +102,7 @@ namespace ts {
 
             // NOTE: this completely disables source maps, but aligns with the behavior of
             //       `emitAssignment` in the old emitter.
-            context.setNodeEmitFlags(declaration, NodeEmitFlags.NoNestedSourceMaps);
+            setEmitFlags(declaration, EmitFlags.NoNestedSourceMaps);
 
             aggregateTransformFlags(declaration);
             declarations.push(declaration);
@@ -147,7 +147,7 @@ namespace ts {
 
             // NOTE: this completely disables source maps, but aligns with the behavior of
             //       `emitAssignment` in the old emitter.
-            context.setNodeEmitFlags(declaration, NodeEmitFlags.NoNestedSourceMaps);
+            setEmitFlags(declaration, EmitFlags.NoNestedSourceMaps);
 
             declarations.push(declaration);
             aggregateTransformFlags(declaration);
@@ -211,7 +211,7 @@ namespace ts {
 
             // NOTE: this completely disables source maps, but aligns with the behavior of
             //       `emitAssignment` in the old emitter.
-            context.setNodeEmitFlags(expression, NodeEmitFlags.NoNestedSourceMaps);
+            setEmitFlags(expression, EmitFlags.NoNestedSourceMaps);
 
             pendingAssignments.push(expression);
             return expression;
@@ -271,8 +271,8 @@ namespace ts {
             }
             else {
                 const name = getMutableClone(<Identifier>target);
-                context.setSourceMapRange(name, target);
-                context.setCommentRange(name, target);
+                setSourceMapRange(name, target);
+                setCommentRange(name, target);
                 emitAssignment(name, value, location, /*original*/ undefined);
             }
         }
diff --git a/src/compiler/transformers/es6.ts b/src/compiler/transformers/es6.ts
index e8ba800e19062..4a6cbd0943443 100644
--- a/src/compiler/transformers/es6.ts
+++ b/src/compiler/transformers/es6.ts
@@ -144,13 +144,6 @@ namespace ts {
             startLexicalEnvironment,
             endLexicalEnvironment,
             hoistVariableDeclaration,
-            getNodeEmitFlags,
-            setNodeEmitFlags,
-            getCommentRange,
-            setCommentRange,
-            getSourceMapRange,
-            setSourceMapRange,
-            setTokenSourceMapRange,
         } = context;
 
         const resolver = context.getEmitResolver();
@@ -185,6 +178,10 @@ namespace ts {
         return transformSourceFile;
 
         function transformSourceFile(node: SourceFile) {
+            if (isDeclarationFile(node)) {
+                return node;
+            }
+
             currentSourceFile = node;
             currentText = node.text;
             return visitNode(node, visitor, isSourceFile);
@@ -408,7 +405,7 @@ namespace ts {
                     enclosingFunction = currentNode;
                     if (currentNode.kind !== SyntaxKind.ArrowFunction) {
                         enclosingNonArrowFunction = currentNode;
-                        if (!(currentNode.emitFlags & NodeEmitFlags.AsyncFunctionBody)) {
+                        if (!(getEmitFlags(currentNode) & EmitFlags.AsyncFunctionBody)) {
                             enclosingNonAsyncFunctionBody = currentNode;
                         }
                     }
@@ -671,19 +668,19 @@ namespace ts {
             // To preserve the behavior of the old emitter, we explicitly indent
             // the body of the function here if it was requested in an earlier
             // transformation.
-            if (getNodeEmitFlags(node) & NodeEmitFlags.Indented) {
-                setNodeEmitFlags(classFunction, NodeEmitFlags.Indented);
+            if (getEmitFlags(node) & EmitFlags.Indented) {
+                setEmitFlags(classFunction, EmitFlags.Indented);
             }
 
             // "inner" and "outer" below are added purely to preserve source map locations from
             // the old emitter
             const inner = createPartiallyEmittedExpression(classFunction);
             inner.end = node.end;
-            setNodeEmitFlags(inner, NodeEmitFlags.NoComments);
+            setEmitFlags(inner, EmitFlags.NoComments);
 
             const outer = createPartiallyEmittedExpression(inner);
             outer.end = skipTrivia(currentText, node.pos);
-            setNodeEmitFlags(outer, NodeEmitFlags.NoComments);
+            setEmitFlags(outer, EmitFlags.NoComments);
 
             return createParen(
                 createCall(
@@ -717,17 +714,17 @@ namespace ts {
             // emit with the original emitter.
             const outer = createPartiallyEmittedExpression(localName);
             outer.end = closingBraceLocation.end;
-            setNodeEmitFlags(outer, NodeEmitFlags.NoComments);
+            setEmitFlags(outer, EmitFlags.NoComments);
 
             const statement = createReturn(outer);
             statement.pos = closingBraceLocation.pos;
-            setNodeEmitFlags(statement, NodeEmitFlags.NoComments | NodeEmitFlags.NoTokenSourceMaps);
+            setEmitFlags(statement, EmitFlags.NoComments | EmitFlags.NoTokenSourceMaps);
             statements.push(statement);
 
             addRange(statements, endLexicalEnvironment());
 
             const block = createBlock(createNodeArray(statements, /*location*/ node.members), /*location*/ undefined, /*multiLine*/ true);
-            setNodeEmitFlags(block, NodeEmitFlags.NoComments);
+            setEmitFlags(block, EmitFlags.NoComments);
             return block;
         }
 
@@ -830,7 +827,7 @@ namespace ts {
             );
 
             if (!constructor) {
-                setNodeEmitFlags(block, NodeEmitFlags.NoComments);
+                setEmitFlags(block, EmitFlags.NoComments);
             }
 
             return block;
@@ -967,27 +964,27 @@ namespace ts {
             // of an initializer, we must emit that expression to preserve side effects.
             if (name.elements.length > 0) {
                 statements.push(
-                    setNodeEmitFlags(
+                    setEmitFlags(
                         createVariableStatement(
                             /*modifiers*/ undefined,
                             createVariableDeclarationList(
                                 flattenParameterDestructuring(context, parameter, temp, visitor)
                             )
                         ),
-                        NodeEmitFlags.CustomPrologue
+                        EmitFlags.CustomPrologue
                     )
                 );
             }
             else if (initializer) {
                 statements.push(
-                    setNodeEmitFlags(
+                    setEmitFlags(
                         createStatement(
                             createAssignment(
                                 temp,
                                 visitNode(initializer, visitor, isExpression)
                             )
                         ),
-                        NodeEmitFlags.CustomPrologue
+                        EmitFlags.CustomPrologue
                     )
                 );
             }
@@ -1008,23 +1005,23 @@ namespace ts {
                     getSynthesizedClone(name),
                     createVoidZero()
                 ),
-                setNodeEmitFlags(
+                setEmitFlags(
                     createBlock([
                         createStatement(
                             createAssignment(
-                                setNodeEmitFlags(getMutableClone(name), NodeEmitFlags.NoSourceMap),
-                                setNodeEmitFlags(initializer, NodeEmitFlags.NoSourceMap | getNodeEmitFlags(initializer)),
+                                setEmitFlags(getMutableClone(name), EmitFlags.NoSourceMap),
+                                setEmitFlags(initializer, EmitFlags.NoSourceMap | getEmitFlags(initializer)),
                                 /*location*/ parameter
                             )
                         )
                     ], /*location*/ parameter),
-                    NodeEmitFlags.SingleLine | NodeEmitFlags.NoTrailingSourceMap | NodeEmitFlags.NoTokenSourceMaps
+                    EmitFlags.SingleLine | EmitFlags.NoTrailingSourceMap | EmitFlags.NoTokenSourceMaps
                 ),
                 /*elseStatement*/ undefined,
                 /*location*/ parameter
             );
             statement.startsOnNewLine = true;
-            setNodeEmitFlags(statement, NodeEmitFlags.NoTokenSourceMaps | NodeEmitFlags.NoTrailingSourceMap | NodeEmitFlags.CustomPrologue);
+            setEmitFlags(statement, EmitFlags.NoTokenSourceMaps | EmitFlags.NoTrailingSourceMap | EmitFlags.CustomPrologue);
             statements.push(statement);
         }
 
@@ -1057,7 +1054,7 @@ namespace ts {
 
             // `declarationName` is the name of the local declaration for the parameter.
             const declarationName = getMutableClone(<Identifier>parameter.name);
-            setNodeEmitFlags(declarationName, NodeEmitFlags.NoSourceMap);
+            setEmitFlags(declarationName, EmitFlags.NoSourceMap);
 
             // `expressionName` is the name of the parameter used in expressions.
             const expressionName = getSynthesizedClone(<Identifier>parameter.name);
@@ -1066,7 +1063,7 @@ namespace ts {
 
             // var param = [];
             statements.push(
-                setNodeEmitFlags(
+                setEmitFlags(
                     createVariableStatement(
                         /*modifiers*/ undefined,
                         createVariableDeclarationList([
@@ -1078,7 +1075,7 @@ namespace ts {
                         ]),
                         /*location*/ parameter
                     ),
-                    NodeEmitFlags.CustomPrologue
+                    EmitFlags.CustomPrologue
                 )
             );
 
@@ -1111,7 +1108,7 @@ namespace ts {
                 ])
             );
 
-            setNodeEmitFlags(forStatement, NodeEmitFlags.CustomPrologue);
+            setEmitFlags(forStatement, EmitFlags.CustomPrologue);
             startOnNewLine(forStatement);
             statements.push(forStatement);
         }
@@ -1136,7 +1133,7 @@ namespace ts {
                     ])
                 );
 
-                setNodeEmitFlags(captureThisStatement, NodeEmitFlags.NoComments | NodeEmitFlags.CustomPrologue);
+                setEmitFlags(captureThisStatement, EmitFlags.NoComments | EmitFlags.CustomPrologue);
                 setSourceMapRange(captureThisStatement, node);
                 statements.push(captureThisStatement);
             }
@@ -1200,7 +1197,7 @@ namespace ts {
             const sourceMapRange = getSourceMapRange(member);
 
             const func = transformFunctionLikeToExpression(member, /*location*/ member, /*name*/ undefined);
-            setNodeEmitFlags(func, NodeEmitFlags.NoComments);
+            setEmitFlags(func, EmitFlags.NoComments);
             setSourceMapRange(func, sourceMapRange);
 
             const statement = createStatement(
@@ -1221,7 +1218,7 @@ namespace ts {
             // The location for the statement is used to emit comments only.
             // No source map should be emitted for this statement to align with the
             // old emitter.
-            setNodeEmitFlags(statement, NodeEmitFlags.NoSourceMap);
+            setEmitFlags(statement, EmitFlags.NoSourceMap);
             return statement;
         }
 
@@ -1240,7 +1237,7 @@ namespace ts {
             // The location for the statement is used to emit source maps only.
             // No comments should be emitted for this statement to align with the
             // old emitter.
-            setNodeEmitFlags(statement, NodeEmitFlags.NoComments);
+            setEmitFlags(statement, EmitFlags.NoComments);
             return statement;
         }
 
@@ -1254,11 +1251,11 @@ namespace ts {
             // To align with source maps in the old emitter, the receiver and property name
             // arguments are both mapped contiguously to the accessor name.
             const target = getMutableClone(receiver);
-            setNodeEmitFlags(target, NodeEmitFlags.NoComments | NodeEmitFlags.NoTrailingSourceMap);
+            setEmitFlags(target, EmitFlags.NoComments | EmitFlags.NoTrailingSourceMap);
             setSourceMapRange(target, firstAccessor.name);
 
             const propertyName = createExpressionForPropertyName(visitNode(firstAccessor.name, visitor, isPropertyName));
-            setNodeEmitFlags(propertyName, NodeEmitFlags.NoComments | NodeEmitFlags.NoLeadingSourceMap);
+            setEmitFlags(propertyName, EmitFlags.NoComments | EmitFlags.NoLeadingSourceMap);
             setSourceMapRange(propertyName, firstAccessor.name);
 
             const properties: ObjectLiteralElementLike[] = [];
@@ -1309,7 +1306,7 @@ namespace ts {
             }
 
             const func = transformFunctionLikeToExpression(node, /*location*/ node, /*name*/ undefined);
-            setNodeEmitFlags(func, NodeEmitFlags.CapturesThis);
+            setEmitFlags(func, EmitFlags.CapturesThis);
             return func;
         }
 
@@ -1434,7 +1431,7 @@ namespace ts {
 
                 const expression = visitNode(body, visitor, isExpression);
                 const returnStatement = createReturn(expression, /*location*/ body);
-                setNodeEmitFlags(returnStatement, NodeEmitFlags.NoTokenSourceMaps | NodeEmitFlags.NoTrailingSourceMap | NodeEmitFlags.NoTrailingComments);
+                setEmitFlags(returnStatement, EmitFlags.NoTokenSourceMaps | EmitFlags.NoTrailingSourceMap | EmitFlags.NoTrailingComments);
                 statements.push(returnStatement);
 
                 // To align with the source map emit for the old emitter, we set a custom
@@ -1452,7 +1449,7 @@ namespace ts {
 
             const block = createBlock(createNodeArray(statements, statementsLocation), node.body, multiLine);
             if (!multiLine && singleLine) {
-                setNodeEmitFlags(block, NodeEmitFlags.SingleLine);
+                setEmitFlags(block, EmitFlags.SingleLine);
             }
 
             if (closeBraceLocation) {
@@ -1875,7 +1872,7 @@ namespace ts {
             }
 
             // The old emitter does not emit source maps for the expression
-            setNodeEmitFlags(expression, NodeEmitFlags.NoSourceMap | getNodeEmitFlags(expression));
+            setEmitFlags(expression, EmitFlags.NoSourceMap | getEmitFlags(expression));
 
             // The old emitter does not emit source maps for the block.
             // We add the location to preserve comments.
@@ -1884,7 +1881,7 @@ namespace ts {
                 /*location*/ bodyLocation
             );
 
-            setNodeEmitFlags(body, NodeEmitFlags.NoSourceMap | NodeEmitFlags.NoTokenSourceMaps);
+            setEmitFlags(body, EmitFlags.NoSourceMap | EmitFlags.NoTokenSourceMaps);
 
             const forStatement = createFor(
                 createVariableDeclarationList([
@@ -1902,7 +1899,7 @@ namespace ts {
             );
 
             // Disable trailing source maps for the OpenParenToken to align source map emit with the old emitter.
-            setNodeEmitFlags(forStatement, NodeEmitFlags.NoTokenTrailingSourceMaps);
+            setEmitFlags(forStatement, EmitFlags.NoTokenTrailingSourceMaps);
             return forStatement;
         }
 
@@ -1938,13 +1935,13 @@ namespace ts {
             const expressions: Expression[] = [];
             const assignment = createAssignment(
                 temp,
-                setNodeEmitFlags(
+                setEmitFlags(
                     createObjectLiteral(
                         visitNodes(properties, visitor, isObjectLiteralElementLike, 0, numInitialProperties),
                         /*location*/ undefined,
                         node.multiLine
                     ),
-                    NodeEmitFlags.Indented
+                    EmitFlags.Indented
                 )
             );
             if (node.multiLine) {
@@ -2067,16 +2064,16 @@ namespace ts {
 
             const isAsyncBlockContainingAwait =
                 enclosingNonArrowFunction
-                && (enclosingNonArrowFunction.emitFlags & NodeEmitFlags.AsyncFunctionBody) !== 0
+                && (getEmitFlags(enclosingNonArrowFunction) & EmitFlags.AsyncFunctionBody) !== 0
                 && (node.statement.transformFlags & TransformFlags.ContainsYield) !== 0;
 
-            let loopBodyFlags: NodeEmitFlags = 0;
+            let loopBodyFlags: EmitFlags = 0;
             if (currentState.containsLexicalThis) {
-                loopBodyFlags |= NodeEmitFlags.CapturesThis;
+                loopBodyFlags |= EmitFlags.CapturesThis;
             }
 
             if (isAsyncBlockContainingAwait) {
-                loopBodyFlags |= NodeEmitFlags.AsyncFunctionBody;
+                loopBodyFlags |= EmitFlags.AsyncFunctionBody;
             }
 
             const convertedLoopVariable =
@@ -2087,7 +2084,7 @@ namespace ts {
                             createVariableDeclaration(
                                 functionName,
                                 /*type*/ undefined,
-                                setNodeEmitFlags(
+                                setEmitFlags(
                                     createFunctionExpression(
                                         isAsyncBlockContainingAwait ? createToken(SyntaxKind.AsteriskToken) : undefined,
                                         /*name*/ undefined,
@@ -2480,7 +2477,7 @@ namespace ts {
             // Methods with computed property names are handled in visitObjectLiteralExpression.
             Debug.assert(!isComputedPropertyName(node.name));
             const functionExpression = transformFunctionLikeToExpression(node, /*location*/ moveRangePos(node, -1), /*name*/ undefined);
-            setNodeEmitFlags(functionExpression, NodeEmitFlags.NoLeadingComments | getNodeEmitFlags(functionExpression));
+            setEmitFlags(functionExpression, EmitFlags.NoLeadingComments | getEmitFlags(functionExpression));
             return createPropertyAssignment(
                 node.name,
                 functionExpression,
@@ -2855,7 +2852,7 @@ namespace ts {
          *
          * @param node The node to be printed.
          */
-        function onEmitNode(node: Node, emit: (node: Node) => void) {
+        function onEmitNode(emitContext: EmitContext, node: Node, emitCallback: (emitContext: EmitContext, node: Node) => void) {
             const savedEnclosingFunction = enclosingFunction;
 
             if (enabledSubstitutions & ES6SubstitutionFlags.CapturedThis && isFunctionLike(node)) {
@@ -2863,7 +2860,7 @@ namespace ts {
                 enclosingFunction = node;
             }
 
-            previousOnEmitNode(node, emit);
+            previousOnEmitNode(emitContext, node, emitCallback);
 
             enclosingFunction = savedEnclosingFunction;
         }
@@ -2904,10 +2901,10 @@ namespace ts {
          * @param isExpression A value indicating whether the node is to be used in an expression
          *                     position.
          */
-        function onSubstituteNode(node: Node, isExpression: boolean) {
-            node = previousOnSubstituteNode(node, isExpression);
+        function onSubstituteNode(emitContext: EmitContext, node: Node) {
+            node = previousOnSubstituteNode(emitContext, node);
 
-            if (isExpression) {
+            if (emitContext === EmitContext.Expression) {
                 return substituteExpression(node);
             }
 
@@ -2995,7 +2992,7 @@ namespace ts {
         function substituteThisKeyword(node: PrimaryExpression): PrimaryExpression {
             if (enabledSubstitutions & ES6SubstitutionFlags.CapturedThis
                 && enclosingFunction
-                && enclosingFunction.emitFlags & NodeEmitFlags.CapturesThis) {
+                && getEmitFlags(enclosingFunction) & EmitFlags.CapturesThis) {
                 return createIdentifier("_this", /*location*/ node);
             }
 
@@ -3013,7 +3010,7 @@ namespace ts {
          * @param allowSourceMaps A value indicating whether source maps may be emitted for the name.
          */
         function getLocalName(node: ClassDeclaration | ClassExpression | FunctionDeclaration, allowComments?: boolean, allowSourceMaps?: boolean) {
-            return getDeclarationName(node, allowComments, allowSourceMaps, NodeEmitFlags.LocalName);
+            return getDeclarationName(node, allowComments, allowSourceMaps, EmitFlags.LocalName);
         }
 
         /**
@@ -3022,18 +3019,18 @@ namespace ts {
          * @param node The declaration.
          * @param allowComments Allow comments for the name.
          */
-        function getDeclarationName(node: DeclarationStatement | ClassExpression, allowComments?: boolean, allowSourceMaps?: boolean, emitFlags?: NodeEmitFlags) {
+        function getDeclarationName(node: DeclarationStatement | ClassExpression, allowComments?: boolean, allowSourceMaps?: boolean, emitFlags?: EmitFlags) {
             if (node.name && !isGeneratedIdentifier(node.name)) {
                 const name = getMutableClone(node.name);
-                emitFlags |= getNodeEmitFlags(node.name);
+                emitFlags |= getEmitFlags(node.name);
                 if (!allowSourceMaps) {
-                    emitFlags |= NodeEmitFlags.NoSourceMap;
+                    emitFlags |= EmitFlags.NoSourceMap;
                 }
                 if (!allowComments) {
-                    emitFlags |= NodeEmitFlags.NoComments;
+                    emitFlags |= EmitFlags.NoComments;
                 }
                 if (emitFlags) {
-                    setNodeEmitFlags(name, emitFlags);
+                    setEmitFlags(name, emitFlags);
                 }
                 return name;
             }
diff --git a/src/compiler/transformers/es7.ts b/src/compiler/transformers/es7.ts
index 5d848bc608bad..4d5e96134c40d 100644
--- a/src/compiler/transformers/es7.ts
+++ b/src/compiler/transformers/es7.ts
@@ -9,6 +9,10 @@ namespace ts {
         return transformSourceFile;
 
         function transformSourceFile(node: SourceFile) {
+            if (isDeclarationFile(node)) {
+                return node;
+            }
+
             return visitEachChild(node, visitor, context);
         }
 
diff --git a/src/compiler/transformers/generators.ts b/src/compiler/transformers/generators.ts
index 5f142b6abe96e..6fe3187bee184 100644
--- a/src/compiler/transformers/generators.ts
+++ b/src/compiler/transformers/generators.ts
@@ -231,9 +231,6 @@ namespace ts {
             endLexicalEnvironment,
             hoistFunctionDeclaration,
             hoistVariableDeclaration,
-            setSourceMapRange,
-            setCommentRange,
-            setNodeEmitFlags
         } = context;
 
         const compilerOptions = context.getCompilerOptions();
@@ -294,6 +291,10 @@ namespace ts {
         return transformSourceFile;
 
         function transformSourceFile(node: SourceFile) {
+            if (isDeclarationFile(node)) {
+                return node;
+            }
+
             if (node.transformFlags & TransformFlags.ContainsGenerator) {
                 currentSourceFile = node;
                 node = visitEachChild(node, visitor, context);
@@ -444,7 +445,7 @@ namespace ts {
          */
         function visitFunctionDeclaration(node: FunctionDeclaration): Statement {
             // Currently, we only support generators that were originally async functions.
-            if (node.asteriskToken && node.emitFlags & NodeEmitFlags.AsyncFunctionBody) {
+            if (node.asteriskToken && getEmitFlags(node) & EmitFlags.AsyncFunctionBody) {
                 node = setOriginalNode(
                     createFunctionDeclaration(
                         /*decorators*/ undefined,
@@ -492,7 +493,7 @@ namespace ts {
          */
         function visitFunctionExpression(node: FunctionExpression): Expression {
             // Currently, we only support generators that were originally async functions.
-            if (node.asteriskToken && node.emitFlags & NodeEmitFlags.AsyncFunctionBody) {
+            if (node.asteriskToken && getEmitFlags(node) & EmitFlags.AsyncFunctionBody) {
                 node = setOriginalNode(
                     createFunctionExpression(
                         /*asteriskToken*/ undefined,
@@ -616,7 +617,7 @@ namespace ts {
             }
             else {
                 // Do not hoist custom prologues.
-                if (node.emitFlags & NodeEmitFlags.CustomPrologue) {
+                if (getEmitFlags(node) & EmitFlags.CustomPrologue) {
                     return node;
                 }
 
@@ -1887,9 +1888,9 @@ namespace ts {
             return -1;
         }
 
-        function onSubstituteNode(node: Node, isExpression: boolean): Node {
-            node = previousOnSubstituteNode(node, isExpression);
-            if (isExpression) {
+        function onSubstituteNode(emitContext: EmitContext, node: Node): Node {
+            node = previousOnSubstituteNode(emitContext, node);
+            if (emitContext === EmitContext.Expression) {
                 return substituteExpression(<Expression>node);
             }
             return node;
@@ -2585,7 +2586,7 @@ namespace ts {
                 /*typeArguments*/ undefined,
                 [
                     createThis(),
-                    setNodeEmitFlags(
+                    setEmitFlags(
                         createFunctionExpression(
                             /*asteriskToken*/ undefined,
                             /*name*/ undefined,
@@ -2598,7 +2599,7 @@ namespace ts {
                                 /*multiLine*/ buildResult.length > 0
                             )
                         ),
-                        NodeEmitFlags.ReuseTempVariableScope
+                        EmitFlags.ReuseTempVariableScope
                     )
                 ]
             );
diff --git a/src/compiler/transformers/jsx.ts b/src/compiler/transformers/jsx.ts
index 9e6aa507cce5a..95a4016bb0aeb 100644
--- a/src/compiler/transformers/jsx.ts
+++ b/src/compiler/transformers/jsx.ts
@@ -16,6 +16,10 @@ namespace ts {
          * @param node A SourceFile node.
          */
         function transformSourceFile(node: SourceFile) {
+            if (isDeclarationFile(node)) {
+                return node;
+            }
+
             currentSourceFile = node;
             node = visitEachChild(node, visitor, context);
             currentSourceFile = undefined;
diff --git a/src/compiler/transformers/module/es6.ts b/src/compiler/transformers/module/es6.ts
index 2716165f2d398..09a2890727c58 100644
--- a/src/compiler/transformers/module/es6.ts
+++ b/src/compiler/transformers/module/es6.ts
@@ -12,6 +12,10 @@ namespace ts {
         return transformSourceFile;
 
         function transformSourceFile(node: SourceFile) {
+            if (isDeclarationFile(node)) {
+                return node;
+            }
+
             if (isExternalModule(node) || compilerOptions.isolatedModules) {
                 currentSourceFile = node;
                 return visitEachChild(node, visitor, context);
diff --git a/src/compiler/transformers/module/module.ts b/src/compiler/transformers/module/module.ts
index 53004da2c171e..c4e9b4c31c802 100644
--- a/src/compiler/transformers/module/module.ts
+++ b/src/compiler/transformers/module/module.ts
@@ -15,9 +15,6 @@ namespace ts {
             startLexicalEnvironment,
             endLexicalEnvironment,
             hoistVariableDeclaration,
-            setNodeEmitFlags,
-            getNodeEmitFlags,
-            setSourceMapRange,
         } = context;
 
         const compilerOptions = context.getCompilerOptions();
@@ -54,6 +51,10 @@ namespace ts {
          * @param node The SourceFile node.
          */
         function transformSourceFile(node: SourceFile) {
+            if (isDeclarationFile(node)) {
+                return node;
+            }
+
             if (isExternalModule(node) || compilerOptions.isolatedModules) {
                 currentSourceFile = node;
 
@@ -92,7 +93,7 @@ namespace ts {
 
             const updated = updateSourceFile(node, statements);
             if (hasExportStarsToExportValues) {
-                setNodeEmitFlags(updated, NodeEmitFlags.EmitExportStar | getNodeEmitFlags(node));
+                setEmitFlags(updated, EmitFlags.EmitExportStar | getEmitFlags(node));
             }
 
             return updated;
@@ -116,7 +117,7 @@ namespace ts {
          */
         function transformUMDModule(node: SourceFile) {
             const define = createIdentifier("define");
-            setNodeEmitFlags(define, NodeEmitFlags.UMDDefine);
+            setEmitFlags(define, EmitFlags.UMDDefine);
             return transformAsynchronousModule(node, define, /*moduleName*/ undefined, /*includeNonAmdDependencies*/ false);
         }
 
@@ -220,7 +221,7 @@ namespace ts {
             if (hasExportStarsToExportValues) {
                 // If we have any `export * from ...` declarations
                 // we need to inform the emitter to add the __export helper.
-                setNodeEmitFlags(body, NodeEmitFlags.EmitExportStar);
+                setEmitFlags(body, EmitFlags.EmitExportStar);
             }
 
             return body;
@@ -234,7 +235,7 @@ namespace ts {
                         /*location*/ exportEquals
                     );
 
-                    setNodeEmitFlags(statement, NodeEmitFlags.NoTokenSourceMaps | NodeEmitFlags.NoComments);
+                    setEmitFlags(statement, EmitFlags.NoTokenSourceMaps | EmitFlags.NoComments);
                     statements.push(statement);
                 }
                 else {
@@ -249,7 +250,7 @@ namespace ts {
                         /*location*/ exportEquals
                     );
 
-                    setNodeEmitFlags(statement, NodeEmitFlags.NoComments);
+                    setEmitFlags(statement, EmitFlags.NoComments);
                     statements.push(statement);
                 }
             }
@@ -388,7 +389,7 @@ namespace ts {
 
             // Set emitFlags on the name of the importEqualsDeclaration
             // This is so the printer will not substitute the identifier
-            setNodeEmitFlags(node.name, NodeEmitFlags.NoSubstitution);
+            setEmitFlags(node.name, EmitFlags.NoSubstitution);
             const statements: Statement[] = [];
             if (moduleKind !== ModuleKind.AMD) {
                 if (hasModifier(node, ModifierFlags.Export)) {
@@ -598,7 +599,7 @@ namespace ts {
             }
             else {
                 statements.push(
-                    createExportStatement(node.name, setNodeEmitFlags(getSynthesizedClone(node.name), NodeEmitFlags.LocalName), /*location*/ node)
+                    createExportStatement(node.name, setEmitFlags(getSynthesizedClone(node.name), EmitFlags.LocalName), /*location*/ node)
                 );
             }
         }
@@ -813,7 +814,7 @@ namespace ts {
                 )],
                     /*location*/ node
             );
-            setNodeEmitFlags(transformedStatement, NodeEmitFlags.NoComments);
+            setEmitFlags(transformedStatement, EmitFlags.NoComments);
             statements.push(transformedStatement);
         }
 
@@ -821,14 +822,14 @@ namespace ts {
             return node.name ? getSynthesizedClone(node.name) : getGeneratedNameForNode(node);
         }
 
-        function onEmitNode(node: Node, emit: (node: Node) => void): void {
+        function onEmitNode(emitContext: EmitContext, node: Node, emitCallback: (emitContext: EmitContext, node: Node) => void): void {
             if (node.kind === SyntaxKind.SourceFile) {
                 bindingNameExportSpecifiersMap = bindingNameExportSpecifiersForFileMap[getOriginalNodeId(node)];
-                previousOnEmitNode(node, emit);
+                previousOnEmitNode(emitContext, node, emitCallback);
                 bindingNameExportSpecifiersMap = undefined;
             }
             else {
-                previousOnEmitNode(node, emit);
+                previousOnEmitNode(emitContext, node, emitCallback);
             }
         }
 
@@ -839,9 +840,9 @@ namespace ts {
          * @param isExpression A value indicating whether the node is to be used in an expression
          *                     position.
          */
-        function onSubstituteNode(node: Node, isExpression: boolean) {
-            node = previousOnSubstituteNode(node, isExpression);
-            if (isExpression) {
+        function onSubstituteNode(emitContext: EmitContext, node: Node) {
+            node = previousOnSubstituteNode(emitContext, node);
+            if (emitContext === EmitContext.Expression) {
                 return substituteExpression(<Expression>node);
             }
             else if (isShorthandPropertyAssignment(node)) {
@@ -890,7 +891,7 @@ namespace ts {
             // If the left-hand-side of the binaryExpression is an identifier and its is export through export Specifier
             if (isIdentifier(left) && isAssignmentOperator(node.operatorToken.kind)) {
                 if (bindingNameExportSpecifiersMap && hasProperty(bindingNameExportSpecifiersMap, left.text)) {
-                    setNodeEmitFlags(node, NodeEmitFlags.NoSubstitution);
+                    setEmitFlags(node, EmitFlags.NoSubstitution);
                     let nestedExportAssignment: BinaryExpression;
                     for (const specifier of bindingNameExportSpecifiersMap[left.text]) {
                         nestedExportAssignment = nestedExportAssignment ?
@@ -910,7 +911,7 @@ namespace ts {
             const operand = node.operand;
             if (isIdentifier(operand) && bindingNameExportSpecifiersForFileMap) {
                 if (bindingNameExportSpecifiersMap && hasProperty(bindingNameExportSpecifiersMap, operand.text)) {
-                    setNodeEmitFlags(node, NodeEmitFlags.NoSubstitution);
+                    setEmitFlags(node, EmitFlags.NoSubstitution);
                     let transformedUnaryExpression: BinaryExpression;
                     if (node.kind === SyntaxKind.PostfixUnaryExpression) {
                         transformedUnaryExpression = createBinary(
@@ -920,7 +921,7 @@ namespace ts {
                             /*location*/ node
                         );
                         // We have to set no substitution flag here to prevent visit the binary expression and substitute it again as we will preform all necessary substitution in here
-                        setNodeEmitFlags(transformedUnaryExpression, NodeEmitFlags.NoSubstitution);
+                        setEmitFlags(transformedUnaryExpression, EmitFlags.NoSubstitution);
                     }
                     let nestedExportAssignment: BinaryExpression;
                     for (const specifier of bindingNameExportSpecifiersMap[operand.text]) {
@@ -935,9 +936,9 @@ namespace ts {
         }
 
         function trySubstituteExportedName(node: Identifier) {
-            const emitFlags = getNodeEmitFlags(node);
-            if ((emitFlags & NodeEmitFlags.LocalName) === 0) {
-                const container = resolver.getReferencedExportContainer(node, (emitFlags & NodeEmitFlags.ExportName) !== 0);
+            const emitFlags = getEmitFlags(node);
+            if ((emitFlags & EmitFlags.LocalName) === 0) {
+                const container = resolver.getReferencedExportContainer(node, (emitFlags & EmitFlags.ExportName) !== 0);
                 if (container) {
                     if (container.kind === SyntaxKind.SourceFile) {
                         return createPropertyAccess(
@@ -953,7 +954,7 @@ namespace ts {
         }
 
         function trySubstituteImportedName(node: Identifier): Expression {
-            if ((getNodeEmitFlags(node) & NodeEmitFlags.LocalName) === 0) {
+            if ((getEmitFlags(node) & EmitFlags.LocalName) === 0) {
                 const declaration = resolver.getReferencedImportDeclaration(node);
                 if (declaration) {
                     if (isImportClause(declaration)) {
@@ -1077,7 +1078,7 @@ namespace ts {
                 if (includeNonAmdDependencies && importAliasName) {
                     // Set emitFlags on the name of the classDeclaration
                     // This is so that when printer will not substitute the identifier
-                    setNodeEmitFlags(importAliasName, NodeEmitFlags.NoSubstitution);
+                    setEmitFlags(importAliasName, EmitFlags.NoSubstitution);
                     aliasedModuleNames.push(externalModuleName);
                     importAliasNames.push(createParameter(importAliasName));
                 }
diff --git a/src/compiler/transformers/module/system.ts b/src/compiler/transformers/module/system.ts
index 5e3b028122775..4a137c89a9336 100644
--- a/src/compiler/transformers/module/system.ts
+++ b/src/compiler/transformers/module/system.ts
@@ -10,8 +10,6 @@ namespace ts {
         }
 
         const {
-            getNodeEmitFlags,
-            setNodeEmitFlags,
             startLexicalEnvironment,
             endLexicalEnvironment,
             hoistVariableDeclaration,
@@ -50,6 +48,10 @@ namespace ts {
         return transformSourceFile;
 
         function transformSourceFile(node: SourceFile) {
+            if (isDeclarationFile(node)) {
+                return node;
+            }
+
             if (isExternalModule(node) || compilerOptions.isolatedModules) {
                 currentSourceFile = node;
                 currentNode = node;
@@ -116,9 +118,9 @@ namespace ts {
                     createParameter(contextObjectForFile)
                 ],
                 /*type*/ undefined,
-                setNodeEmitFlags(
+                setEmitFlags(
                     createBlock(statements, /*location*/ undefined, /*multiLine*/ true),
-                    NodeEmitFlags.EmitEmitHelpers
+                    EmitFlags.EmitEmitHelpers
                 )
             );
 
@@ -135,7 +137,7 @@ namespace ts {
                             : [dependencies, body]
                     )
                 )
-            ], /*nodeEmitFlags*/ ~NodeEmitFlags.EmitEmitHelpers & getNodeEmitFlags(node));
+            ], /*nodeEmitFlags*/ ~EmitFlags.EmitEmitHelpers & getEmitFlags(node));
         }
 
         /**
@@ -984,14 +986,14 @@ namespace ts {
         // Substitutions
         //
 
-        function onEmitNode(node: Node, emit: (node: Node) => void): void {
+        function onEmitNode(emitContext: EmitContext, node: Node, emitCallback: (emitContext: EmitContext, node: Node) => void): void {
             if (node.kind === SyntaxKind.SourceFile) {
                 exportFunctionForFile = exportFunctionForFileMap[getOriginalNodeId(node)];
-                previousOnEmitNode(node, emit);
+                previousOnEmitNode(emitContext, node, emitCallback);
                 exportFunctionForFile = undefined;
             }
             else {
-                previousOnEmitNode(node, emit);
+                previousOnEmitNode(emitContext, node, emitCallback);
             }
         }
 
@@ -1002,9 +1004,9 @@ namespace ts {
          * @param isExpression A value indicating whether the node is to be used in an expression
          *                     position.
          */
-        function onSubstituteNode(node: Node, isExpression: boolean) {
-            node = previousOnSubstituteNode(node, isExpression);
-            if (isExpression) {
+        function onSubstituteNode(emitContext: EmitContext, node: Node) {
+            node = previousOnSubstituteNode(emitContext, node);
+            if (emitContext === EmitContext.Expression) {
                 return substituteExpression(<Expression>node);
             }
 
@@ -1053,7 +1055,7 @@ namespace ts {
         }
 
         function substituteAssignmentExpression(node: BinaryExpression): Expression {
-            setNodeEmitFlags(node, NodeEmitFlags.NoSubstitution);
+            setEmitFlags(node, EmitFlags.NoSubstitution);
 
             const left = node.left;
             switch (left.kind) {
@@ -1176,7 +1178,7 @@ namespace ts {
                 const exportDeclaration = resolver.getReferencedExportContainer(<Identifier>operand);
                 if (exportDeclaration) {
                     const expr = createPrefix(node.operator, operand, node);
-                    setNodeEmitFlags(expr, NodeEmitFlags.NoSubstitution);
+                    setEmitFlags(expr, EmitFlags.NoSubstitution);
                     const call = createExportExpression(<Identifier>operand, expr);
                     if (node.kind === SyntaxKind.PrefixUnaryExpression) {
                         return call;
@@ -1241,7 +1243,7 @@ namespace ts {
                             ]),
                             m,
                             createBlock([
-                                setNodeEmitFlags(
+                                setEmitFlags(
                                     createIf(
                                         condition,
                                         createStatement(
@@ -1251,7 +1253,7 @@ namespace ts {
                                             )
                                         )
                                     ),
-                                    NodeEmitFlags.SingleLine
+                                    EmitFlags.SingleLine
                                 )
                             ])
                         ),
@@ -1393,10 +1395,10 @@ namespace ts {
             hoistBindingElement(node, /*isExported*/ false);
         }
 
-        function updateSourceFile(node: SourceFile, statements: Statement[], nodeEmitFlags: NodeEmitFlags) {
+        function updateSourceFile(node: SourceFile, statements: Statement[], nodeEmitFlags: EmitFlags) {
             const updated = getMutableClone(node);
             updated.statements = createNodeArray(statements, node.statements);
-            setNodeEmitFlags(updated, nodeEmitFlags);
+            setEmitFlags(updated, nodeEmitFlags);
             return updated;
         }
     }
diff --git a/src/compiler/transformers/ts.ts b/src/compiler/transformers/ts.ts
index 1d01e51f6d8d7..054b1e4608bfc 100644
--- a/src/compiler/transformers/ts.ts
+++ b/src/compiler/transformers/ts.ts
@@ -24,10 +24,6 @@ namespace ts {
 
     export function transformTypeScript(context: TransformationContext) {
         const {
-            getNodeEmitFlags,
-            setNodeEmitFlags,
-            setCommentRange,
-            setSourceMapRange,
             startLexicalEnvironment,
             endLexicalEnvironment,
             hoistVariableDeclaration,
@@ -46,6 +42,10 @@ namespace ts {
         context.onEmitNode = onEmitNode;
         context.onSubstituteNode = onSubstituteNode;
 
+        // Enable substitution for property/element access to emit const enum values.
+        context.enableSubstitution(SyntaxKind.PropertyAccessExpression);
+        context.enableSubstitution(SyntaxKind.ElementAccessExpression);
+
         // These variables contain state that changes as we descend into the tree.
         let currentSourceFile: SourceFile;
         let currentNamespace: ModuleDeclaration;
@@ -85,6 +85,10 @@ namespace ts {
          * @param node A SourceFile node.
          */
         function transformSourceFile(node: SourceFile) {
+            if (isDeclarationFile(node)) {
+                return node;
+            }
+
             return visitNode(node, visitor, isSourceFile);
         }
 
@@ -449,7 +453,7 @@ namespace ts {
                 node = visitEachChild(node, visitor, context);
             }
 
-            setNodeEmitFlags(node, NodeEmitFlags.EmitEmitHelpers | node.emitFlags);
+            setEmitFlags(node, EmitFlags.EmitEmitHelpers | getEmitFlags(node));
             return node;
         }
 
@@ -521,7 +525,7 @@ namespace ts {
                 // To better align with the old emitter, we should not emit a trailing source map
                 // entry if the class has static properties.
                 if (staticProperties.length > 0) {
-                    setNodeEmitFlags(classDeclaration, NodeEmitFlags.NoTrailingSourceMap | getNodeEmitFlags(classDeclaration));
+                    setEmitFlags(classDeclaration, EmitFlags.NoTrailingSourceMap | getEmitFlags(classDeclaration));
                 }
 
                 statements.push(classDeclaration);
@@ -776,7 +780,7 @@ namespace ts {
 
                 // To preserve the behavior of the old emitter, we explicitly indent
                 // the body of a class with static initializers.
-                setNodeEmitFlags(classExpression, NodeEmitFlags.Indented | getNodeEmitFlags(classExpression));
+                setEmitFlags(classExpression, EmitFlags.Indented | getEmitFlags(classExpression));
                 expressions.push(startOnNewLine(createAssignment(temp, classExpression)));
                 addRange(expressions, generateInitializedPropertyExpressions(node, staticProperties, temp));
                 expressions.push(startOnNewLine(temp));
@@ -1009,10 +1013,10 @@ namespace ts {
             Debug.assert(isIdentifier(node.name));
             const name = node.name as Identifier;
             const propertyName = getMutableClone(name);
-            setNodeEmitFlags(propertyName, NodeEmitFlags.NoComments | NodeEmitFlags.NoSourceMap);
+            setEmitFlags(propertyName, EmitFlags.NoComments | EmitFlags.NoSourceMap);
 
             const localName = getMutableClone(name);
-            setNodeEmitFlags(localName, NodeEmitFlags.NoComments);
+            setEmitFlags(localName, EmitFlags.NoComments);
 
             return startOnNewLine(
                 createStatement(
@@ -1418,7 +1422,7 @@ namespace ts {
                 moveRangePastDecorators(member)
             );
 
-            setNodeEmitFlags(helper, NodeEmitFlags.NoComments);
+            setEmitFlags(helper, EmitFlags.NoComments);
             return helper;
         }
 
@@ -1467,7 +1471,7 @@ namespace ts {
                 );
 
                 const result = createAssignment(getDeclarationName(node), expression, moveRangePastDecorators(node));
-                setNodeEmitFlags(result, NodeEmitFlags.NoComments);
+                setEmitFlags(result, EmitFlags.NoComments);
                 return result;
             }
             // Emit the call to __decorate. Given the class:
@@ -1491,7 +1495,7 @@ namespace ts {
                     moveRangePastDecorators(node)
                 );
 
-                setNodeEmitFlags(result, NodeEmitFlags.NoComments);
+                setEmitFlags(result, EmitFlags.NoComments);
                 return result;
             }
         }
@@ -1521,7 +1525,7 @@ namespace ts {
                         transformDecorator(decorator),
                         parameterOffset,
                         /*location*/ decorator.expression);
-                    setNodeEmitFlags(helper, NodeEmitFlags.NoComments);
+                    setEmitFlags(helper, EmitFlags.NoComments);
                     expressions.push(helper);
                 }
             }
@@ -2324,11 +2328,11 @@ namespace ts {
                 if (languageVersion >= ScriptTarget.ES6) {
                     if (resolver.getNodeCheckFlags(node) & NodeCheckFlags.AsyncMethodWithSuperBinding) {
                         enableSubstitutionForAsyncMethodsWithSuper();
-                        setNodeEmitFlags(block, NodeEmitFlags.EmitAdvancedSuperHelper);
+                        setEmitFlags(block, EmitFlags.EmitAdvancedSuperHelper);
                     }
                     else if (resolver.getNodeCheckFlags(node) & NodeCheckFlags.AsyncMethodWithSuper) {
                         enableSubstitutionForAsyncMethodsWithSuper();
-                        setNodeEmitFlags(block, NodeEmitFlags.EmitSuperHelper);
+                        setEmitFlags(block, EmitFlags.EmitSuperHelper);
                     }
                 }
 
@@ -2375,7 +2379,7 @@ namespace ts {
             setOriginalNode(parameter, node);
             setCommentRange(parameter, node);
             setSourceMapRange(parameter, moveRangePastModifiers(node));
-            setNodeEmitFlags(parameter.name, NodeEmitFlags.NoTrailingSourceMap);
+            setEmitFlags(parameter.name, EmitFlags.NoTrailingSourceMap);
 
             return parameter;
         }
@@ -2534,7 +2538,7 @@ namespace ts {
 
             // We request to be advised when the printer is about to print this node. This allows
             // us to set up the correct state for later substitutions.
-            let emitFlags = NodeEmitFlags.AdviseOnEmitNode;
+            let emitFlags = EmitFlags.AdviseOnEmitNode;
 
             // If needed, we should emit a variable declaration for the enum. If we emit
             // a leading variable declaration, we should not emit leading comments for the
@@ -2544,7 +2548,7 @@ namespace ts {
 
                 // We should still emit the comments if we are emitting a system module.
                 if (moduleKind !== ModuleKind.System || currentScope !== currentSourceFile) {
-                    emitFlags |= NodeEmitFlags.NoLeadingComments;
+                    emitFlags |= EmitFlags.NoLeadingComments;
                 }
             }
 
@@ -2584,7 +2588,7 @@ namespace ts {
             );
 
             setOriginalNode(enumStatement, node);
-            setNodeEmitFlags(enumStatement, emitFlags);
+            setEmitFlags(enumStatement, emitFlags);
             statements.push(enumStatement);
 
             if (isNamespaceExport(node)) {
@@ -2736,7 +2740,7 @@ namespace ts {
             //     })(m1 || (m1 = {})); // trailing comment module
             //
             setCommentRange(statement, node);
-            setNodeEmitFlags(statement, NodeEmitFlags.NoTrailingComments);
+            setEmitFlags(statement, EmitFlags.NoTrailingComments);
             statements.push(statement);
         }
 
@@ -2759,7 +2763,7 @@ namespace ts {
 
             // We request to be advised when the printer is about to print this node. This allows
             // us to set up the correct state for later substitutions.
-            let emitFlags = NodeEmitFlags.AdviseOnEmitNode;
+            let emitFlags = EmitFlags.AdviseOnEmitNode;
 
             // If needed, we should emit a variable declaration for the module. If we emit
             // a leading variable declaration, we should not emit leading comments for the
@@ -2768,7 +2772,7 @@ namespace ts {
                 addVarForEnumOrModuleDeclaration(statements, node);
                 // We should still emit the comments if we are emitting a system module.
                 if (moduleKind !== ModuleKind.System || currentScope !== currentSourceFile) {
-                    emitFlags |= NodeEmitFlags.NoLeadingComments;
+                    emitFlags |= EmitFlags.NoLeadingComments;
                 }
             }
 
@@ -2820,7 +2824,7 @@ namespace ts {
             );
 
             setOriginalNode(moduleStatement, node);
-            setNodeEmitFlags(moduleStatement, emitFlags);
+            setEmitFlags(moduleStatement, emitFlags);
             statements.push(moduleStatement);
             return statements;
         }
@@ -2895,7 +2899,7 @@ namespace ts {
             // })(hello || (hello = {}));
             // We only want to emit comment on the namespace which contains block body itself, not the containing namespaces.
             if (body.kind !== SyntaxKind.ModuleBlock) {
-                setNodeEmitFlags(block, block.emitFlags | NodeEmitFlags.NoComments);
+                setEmitFlags(block, getEmitFlags(block) | EmitFlags.NoComments);
             }
             return block;
         }
@@ -2936,7 +2940,7 @@ namespace ts {
             }
 
             const moduleReference = createExpressionFromEntityName(<EntityName>node.moduleReference);
-            setNodeEmitFlags(moduleReference, NodeEmitFlags.NoComments | NodeEmitFlags.NoNestedComments);
+            setEmitFlags(moduleReference, EmitFlags.NoComments | EmitFlags.NoNestedComments);
 
             if (isNamedExternalModuleExport(node) || !isNamespaceExport(node)) {
                 //  export var ${name} = ${moduleReference};
@@ -3048,15 +3052,15 @@ namespace ts {
 
         function getNamespaceMemberName(name: Identifier, allowComments?: boolean, allowSourceMaps?: boolean): Expression {
             const qualifiedName = createPropertyAccess(currentNamespaceContainerName, getSynthesizedClone(name), /*location*/ name);
-            let emitFlags: NodeEmitFlags;
+            let emitFlags: EmitFlags;
             if (!allowComments) {
-                emitFlags |= NodeEmitFlags.NoComments;
+                emitFlags |= EmitFlags.NoComments;
             }
             if (!allowSourceMaps) {
-                emitFlags |= NodeEmitFlags.NoSourceMap;
+                emitFlags |= EmitFlags.NoSourceMap;
             }
             if (emitFlags) {
-                setNodeEmitFlags(qualifiedName, emitFlags);
+                setEmitFlags(qualifiedName, emitFlags);
             }
             return qualifiedName;
         }
@@ -3093,7 +3097,7 @@ namespace ts {
          * @param allowComments A value indicating whether comments may be emitted for the name.
          */
         function getLocalName(node: DeclarationStatement | ClassExpression, noSourceMaps?: boolean, allowComments?: boolean) {
-            return getDeclarationName(node, allowComments, !noSourceMaps, NodeEmitFlags.LocalName);
+            return getDeclarationName(node, allowComments, !noSourceMaps, EmitFlags.LocalName);
         }
 
         /**
@@ -3111,7 +3115,7 @@ namespace ts {
                 return getNamespaceMemberName(getDeclarationName(node), allowComments, !noSourceMaps);
             }
 
-            return getDeclarationName(node, allowComments, !noSourceMaps, NodeEmitFlags.ExportName);
+            return getDeclarationName(node, allowComments, !noSourceMaps, EmitFlags.ExportName);
         }
 
         /**
@@ -3122,20 +3126,20 @@ namespace ts {
          * @param allowSourceMaps A value indicating whether source maps may be emitted for the name.
          * @param emitFlags Additional NodeEmitFlags to specify for the name.
          */
-        function getDeclarationName(node: DeclarationStatement | ClassExpression, allowComments?: boolean, allowSourceMaps?: boolean, emitFlags?: NodeEmitFlags) {
+        function getDeclarationName(node: DeclarationStatement | ClassExpression, allowComments?: boolean, allowSourceMaps?: boolean, emitFlags?: EmitFlags) {
             if (node.name) {
                 const name = getMutableClone(node.name);
-                emitFlags |= getNodeEmitFlags(node.name);
+                emitFlags |= getEmitFlags(node.name);
                 if (!allowSourceMaps) {
-                    emitFlags |= NodeEmitFlags.NoSourceMap;
+                    emitFlags |= EmitFlags.NoSourceMap;
                 }
 
                 if (!allowComments) {
-                    emitFlags |= NodeEmitFlags.NoComments;
+                    emitFlags |= EmitFlags.NoComments;
                 }
 
                 if (emitFlags) {
-                    setNodeEmitFlags(name, emitFlags);
+                    setEmitFlags(name, emitFlags);
                 }
 
                 return name;
@@ -3231,7 +3235,7 @@ namespace ts {
          * @param node The node to emit.
          * @param emit A callback used to emit the node in the printer.
          */
-        function onEmitNode(node: Node, emit: (node: Node) => void): void {
+        function onEmitNode(emitContext: EmitContext, node: Node, emitCallback: (emitContext: EmitContext, node: Node) => void): void {
             const savedApplicableSubstitutions = applicableSubstitutions;
             const savedCurrentSuperContainer = currentSuperContainer;
             // If we need to support substitutions for `super` in an async method,
@@ -3248,7 +3252,7 @@ namespace ts {
                 applicableSubstitutions |= TypeScriptSubstitutionFlags.NonQualifiedEnumMembers;
             }
 
-            previousOnEmitNode(node, emit);
+            previousOnEmitNode(emitContext, node, emitCallback);
 
             applicableSubstitutions = savedApplicableSubstitutions;
             currentSuperContainer = savedCurrentSuperContainer;
@@ -3261,9 +3265,9 @@ namespace ts {
          * @param isExpression A value indicating whether the node is to be used in an expression
          *                     position.
          */
-        function onSubstituteNode(node: Node, isExpression: boolean) {
-            node = previousOnSubstituteNode(node, isExpression);
-            if (isExpression) {
+        function onSubstituteNode(emitContext: EmitContext, node: Node) {
+            node = previousOnSubstituteNode(emitContext, node);
+            if (emitContext === EmitContext.Expression) {
                 return substituteExpression(<Expression>node);
             }
             else if (isShorthandPropertyAssignment(node)) {
@@ -3294,17 +3298,15 @@ namespace ts {
             switch (node.kind) {
                 case SyntaxKind.Identifier:
                     return substituteExpressionIdentifier(<Identifier>node);
-            }
-
-            if (enabledSubstitutions & TypeScriptSubstitutionFlags.AsyncMethodsWithSuper) {
-                switch (node.kind) {
-                    case SyntaxKind.CallExpression:
+                case SyntaxKind.PropertyAccessExpression:
+                    return substitutePropertyAccessExpression(<PropertyAccessExpression>node);
+                case SyntaxKind.ElementAccessExpression:
+                    return substituteElementAccessExpression(<ElementAccessExpression>node);
+                case SyntaxKind.CallExpression:
+                    if (enabledSubstitutions & TypeScriptSubstitutionFlags.AsyncMethodsWithSuper) {
                         return substituteCallExpression(<CallExpression>node);
-                    case SyntaxKind.PropertyAccessExpression:
-                        return substitutePropertyAccessExpression(<PropertyAccessExpression>node);
-                    case SyntaxKind.ElementAccessExpression:
-                        return substituteElementAccessExpression(<ElementAccessExpression>node);
-                }
+                    }
+                    break;
             }
 
             return node;
@@ -3342,7 +3344,7 @@ namespace ts {
 
         function trySubstituteNamespaceExportedName(node: Identifier): Expression {
             // If this is explicitly a local name, do not substitute.
-            if (enabledSubstitutions & applicableSubstitutions && (getNodeEmitFlags(node) & NodeEmitFlags.LocalName) === 0) {
+            if (enabledSubstitutions & applicableSubstitutions && (getEmitFlags(node) & EmitFlags.LocalName) === 0) {
                 // If we are nested within a namespace declaration, we may need to qualifiy
                 // an identifier that is exported from a merged namespace.
                 const container = resolver.getReferencedExportContainer(node, /*prefixLocals*/ false);
@@ -3381,7 +3383,7 @@ namespace ts {
         }
 
         function substitutePropertyAccessExpression(node: PropertyAccessExpression) {
-            if (node.expression.kind === SyntaxKind.SuperKeyword) {
+            if (enabledSubstitutions & TypeScriptSubstitutionFlags.AsyncMethodsWithSuper && node.expression.kind === SyntaxKind.SuperKeyword) {
                 const flags = getSuperContainerAsyncMethodFlags();
                 if (flags) {
                     return createSuperAccessInAsyncMethod(
@@ -3392,11 +3394,11 @@ namespace ts {
                 }
             }
 
-            return node;
+            return substituteConstantValue(node);
         }
 
         function substituteElementAccessExpression(node: ElementAccessExpression) {
-            if (node.expression.kind === SyntaxKind.SuperKeyword) {
+            if (enabledSubstitutions & TypeScriptSubstitutionFlags.AsyncMethodsWithSuper && node.expression.kind === SyntaxKind.SuperKeyword) {
                 const flags = getSuperContainerAsyncMethodFlags();
                 if (flags) {
                     return createSuperAccessInAsyncMethod(
@@ -3407,9 +3409,39 @@ namespace ts {
                 }
             }
 
+            return substituteConstantValue(node);
+        }
+
+        function substituteConstantValue(node: PropertyAccessExpression | ElementAccessExpression): LeftHandSideExpression {
+            const constantValue = tryGetConstEnumValue(node);
+            if (constantValue !== undefined) {
+                const substitute = createLiteral(constantValue);
+                setSourceMapRange(substitute, node);
+                setCommentRange(substitute, node);
+                if (!compilerOptions.removeComments) {
+                    const propertyName = isPropertyAccessExpression(node)
+                        ? declarationNameToString(node.name)
+                        : getTextOfNode(node.argumentExpression);
+                    substitute.trailingComment = ` ${propertyName} `;
+                }
+
+                setConstantValue(node, constantValue);
+                return substitute;
+            }
+
             return node;
         }
 
+        function tryGetConstEnumValue(node: Node): number {
+            if (compilerOptions.isolatedModules) {
+                return undefined;
+            }
+
+            return isPropertyAccessExpression(node) || isElementAccessExpression(node)
+                ? resolver.getConstantValue(<PropertyAccessExpression | ElementAccessExpression>node)
+                : undefined;
+        }
+
         function createSuperAccessInAsyncMethod(argumentExpression: Expression, flags: NodeCheckFlags, location: TextRange): LeftHandSideExpression {
             if (flags & NodeCheckFlags.AsyncMethodWithSuperBinding) {
                 return createPropertyAccess(
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 7629f12423115..f6d791769925e 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -494,10 +494,7 @@ namespace ts {
         /* @internal */ nextContainer?: Node;           // Next container in declaration order (initialized by binding)
         /* @internal */ localSymbol?: Symbol;           // Local symbol declared by node (initialized by binding only for exported nodes)
         /* @internal */ flowNode?: FlowNode;            // Associated FlowNode (initialized by binding)
-        /* @internal */ transformId?: number;           // Associates transient transformation properties with a specific transformation (initialized by transformation).
-        /* @internal */ emitFlags?: NodeEmitFlags;      // Transient emit flags for a synthesized node (initialized by transformation).
-        /* @internal */ sourceMapRange?: TextRange;     // Transient custom sourcemap range for a synthesized node (initialized by transformation).
-        /* @internal */ commentRange?: TextRange;       // Transient custom comment range for a synthesized node (initialized by transformation).
+        /* @internal */ emitNode?: EmitNode;            // Associated EmitNode (initialized by transforms)
     }
 
     export interface NodeArray<T extends Node> extends Array<T>, TextRange {
@@ -3175,7 +3172,17 @@ namespace ts {
     }
 
     /* @internal */
-    export const enum NodeEmitFlags {
+    export interface EmitNode {
+        flags?: EmitFlags;
+        commentRange?: TextRange;
+        sourceMapRange?: TextRange;
+        tokenSourceMapRanges?: Map<TextRange>;
+        annotatedNodes?: Node[];                // Tracks Parse-tree nodes with EmitNodes for eventual cleanup.
+        constantValue?: number;
+    }
+
+    /* @internal */
+    export const enum EmitFlags {
         EmitEmitHelpers = 1 << 0,                // Any emit helpers should be written to this node.
         EmitExportStar = 1 << 1,                 // The export * helper should be written to this node.
         EmitSuperHelper = 1 << 2,                // Emit the basic _super helper for async methods.
@@ -3205,6 +3212,14 @@ namespace ts {
         CustomPrologue = 1 << 23,                // Treat the statement as if it were a prologue directive (NOTE: Prologue directives are *not* transformed).
     }
 
+    /* @internal */
+    export const enum EmitContext {
+        SourceFile,         // Emitting a SourceFile
+        Expression,         // Emitting an Expression
+        IdentifierName,     // Emitting an IdentifierName
+        Unspecified,        // Emitting an otherwise unspecified node
+    }
+
     /** Additional context provided to `visitEachChild` */
     /* @internal */
     export interface LexicalEnvironment {
diff --git a/tests/baselines/reference/constEnumToStringWithComments.js b/tests/baselines/reference/constEnumToStringWithComments.js
index c01e75cb923fc..f0fbc8663859e 100644
--- a/tests/baselines/reference/constEnumToStringWithComments.js
+++ b/tests/baselines/reference/constEnumToStringWithComments.js
@@ -23,15 +23,15 @@ let c1 = Foo["C"].toString();
 
 
 //// [constEnumToStringWithComments.js]
-var x0 = 100 /* X */..toString();
-var x1 = 100 /* "X" */..toString();
+var x0 = 100 /* X */.toString();
+var x1 = 100 /* "X" */.toString();
 var y0 = 0.5 /* Y */.toString();
 var y1 = 0.5 /* "Y" */.toString();
-var z0 = 2 /* Z */..toString();
-var z1 = 2 /* "Z" */..toString();
-var a0 = -1 /* A */..toString();
-var a1 = -1 /* "A" */..toString();
+var z0 = 2 /* Z */.toString();
+var z1 = 2 /* "Z" */.toString();
+var a0 = -1 /* A */.toString();
+var a1 = -1 /* "A" */.toString();
 var b0 = -1.5 /* B */.toString();
 var b1 = -1.5 /* "B" */.toString();
-var c0 = -1 /* C */..toString();
-var c1 = -1 /* "C" */..toString();
+var c0 = -1 /* C */.toString();
+var c1 = -1 /* "C" */.toString();