diff --git a/docs/CMakeLists.txt b/docs/CMakeLists.txt
index d94e7b94cc560..d91a99b772ea6 100644
--- a/docs/CMakeLists.txt
+++ b/docs/CMakeLists.txt
@@ -82,7 +82,7 @@ if(LITRE_EXECUTABLE)
     VERBATIM
     )
 
-  # Only update the real top-level CMakeLists.txt if something  changed
+  # Only update the real top-level CMakeLists.txt if something changed
   add_custom_command(
     OUTPUT
       "litre-tests/CMakeLists.txt"
diff --git a/docs/ErrorHandling.rst b/docs/ErrorHandling.rst
index 547af4def253a..a7b14bd387477 100644
--- a/docs/ErrorHandling.rst
+++ b/docs/ErrorHandling.rst
@@ -578,7 +578,7 @@ of failability.
 
 One limitation of this approach is that we need to be able to reconstruct
 the selector to use when an overload of a method is introduced.  For this
-reason, the import is likely to be limited to methods where  the error
+reason, the import is likely to be limited to methods where the error
 parameter is the last one and the corresponding selector
 chunk is either ``error:`` or the first chunk (see below).  Empirically,
 this seems to do the right thing for all but two sets of APIs in the
diff --git a/docs/TypeChecker.rst b/docs/TypeChecker.rst
index fb1856eb30645..21fd3b77a1319 100644
--- a/docs/TypeChecker.rst
+++ b/docs/TypeChecker.rst
@@ -106,7 +106,7 @@ the Swift type system:
   flavors of equality constraints: 
 
     - Exact equality constraints, or  "binding", written ``T0 := X``
-      for some type variable ``T0`` and  type ``X``, which requires
+      for some type variable ``T0`` and type ``X``, which requires
       that ``T0`` be exactly identical to ``X``;
     - Equality constraints, written ``X == Y`` for types ``X`` and
       ``Y``, which require ``X`` and ``Y`` to have the same type,
diff --git a/docs/archive/LangRef.html b/docs/archive/LangRef.html
index fecf8c1e67df7..5ee53490e7106 100644
--- a/docs/archive/LangRef.html
+++ b/docs/archive/LangRef.html
@@ -1093,7 +1093,7 @@ <h3 id="type-function">Function Types</h3>
 
   <p>The result type of a function type must
      be <a href="#materializable">materializable</a>.  The argument type of a
-     function is always required to be parenthesized (a tuple).  The  behavior
+     function is always required to be parenthesized (a tuple).  The behavior
      of function types may be modified with the <a 
       href="#attribute-autoclosure"><tt>autoclosure</tt> attribute</a>.</p>
 
diff --git a/docs/doxygen.intro b/docs/doxygen.intro
index 8d953655bc6ab..f1ff0682a5829 100644
--- a/docs/doxygen.intro
+++ b/docs/doxygen.intro
@@ -4,7 +4,7 @@
 /// Welcome to Swift.
 ///
 /// This documentation describes the @b internal software that makes 
-/// up Swift, not the @b external use of  Swift. There are no instructions
+/// up Swift, not the @b external use of Swift. There are no instructions
 /// here on how to use Swift, only the APIs that make up the software. For usage 
 /// instructions, please see the programmer's guide or reference manual.
 ///
diff --git a/docs/proposals/OptimizerEffects.rst b/docs/proposals/OptimizerEffects.rst
index d5c11835af489..c22b626cf8b18 100644
--- a/docs/proposals/OptimizerEffects.rst
+++ b/docs/proposals/OptimizerEffects.rst
@@ -482,7 +482,7 @@ destructor can have arbitrary side-effects. Therefore, it is not valid to hoist
 the makeUnique in the code without proving that 'T's destructor cannot change
 the uniqueness state. This is trivial for trivial types but requires a more
 sophisticated analysis for class types (and in general cannot be disproved). In
-following example we can only hoist makeUnique if we can prove that  elt's, and
+following example we can only hoist makeUnique if we can prove that elt's, and
 elt2's destructor can't change the uniqueness state of the arrays.::
 
  for i in 0 ..< min(a.size, b.size) {
diff --git a/include/swift/AST/SILOptions.h b/include/swift/AST/SILOptions.h
index fd9916d5f6093..df6811cc56cd4 100644
--- a/include/swift/AST/SILOptions.h
+++ b/include/swift/AST/SILOptions.h
@@ -51,7 +51,7 @@ class SILOptions {
     OptimizeUnchecked
   };
 
-  /// Controls how  perform SIL linking.
+  /// Controls how to perform SIL linking.
   LinkingMode LinkMode = LinkNormal;
 
   /// Remove all runtime assertions during optimizations.
diff --git a/include/swift/AST/Types.h b/include/swift/AST/Types.h
index b49f287f7297e..8b181b29f3cc0 100644
--- a/include/swift/AST/Types.h
+++ b/include/swift/AST/Types.h
@@ -1924,7 +1924,7 @@ class ModuleType : public TypeBase {
 
   // Implement isa/cast/dyncast/etc.
   static bool classof(const TypeBase *T) {
-    return  T->getKind() == TypeKind::Module;
+    return T->getKind() == TypeKind::Module;
   }
   
 private:
diff --git a/include/swift/LLVMPasses/PassesFwd.h b/include/swift/LLVMPasses/PassesFwd.h
index 3b9500dc151bf..bf36b95b5ddcf 100644
--- a/include/swift/LLVMPasses/PassesFwd.h
+++ b/include/swift/LLVMPasses/PassesFwd.h
@@ -1,4 +1,4 @@
-//===--- PassesFwd.h - Creation functions for LLVM  passes ------*- C++ -*-===//
+//===--- PassesFwd.h - Creation functions for LLVM passes -------*- C++ -*-===//
 //
 // This source file is part of the Swift.org open source project
 //
diff --git a/include/swift/SIL/PatternMatch.h b/include/swift/SIL/PatternMatch.h
index 6f1f55c468a4a..9848b691b4a26 100644
--- a/include/swift/SIL/PatternMatch.h
+++ b/include/swift/SIL/PatternMatch.h
@@ -136,7 +136,7 @@ inline match_combine_and<LTy, RTy> m_CombineAnd(const LTy &L, const RTy &R) {
 
 /// Helper class to track the return type of vararg m_CombineOr matcher.
 template <typename ...Arguments>
-struct  OneOf_match;
+struct OneOf_match;
 
 template <typename T0>
 struct OneOf_match<T0> {
@@ -711,8 +711,8 @@ m_Ext(const T0 &Op0) {
 
 /// Matcher for any of the builtin CheckedTrunc instructions.
 template <typename T0>
-inline  typename OneOf_match<BuiltinApplyTy<T0>, BuiltinApplyTy<T0>,
-                             BuiltinApplyTy<T0>, BuiltinApplyTy<T0>>::Ty
+inline typename OneOf_match<BuiltinApplyTy<T0>, BuiltinApplyTy<T0>,
+                            BuiltinApplyTy<T0>, BuiltinApplyTy<T0>>::Ty
 m_CheckedTrunc(const T0 &Op0) {
   return m_UToSCheckedTrunc(Op0) || m_SToUCheckedTrunc(Op0) ||
          m_UToUCheckedTrunc(Op0) || m_SToSCheckedTrunc(Op0);
diff --git a/include/swift/SIL/Projection.h b/include/swift/SIL/Projection.h
index de8fb5b3c01f2..3df6b0c3d7de9 100644
--- a/include/swift/SIL/Projection.h
+++ b/include/swift/SIL/Projection.h
@@ -1,4 +1,4 @@
-//===--- Projection.h - Utilities for working with  Projections -*- C++ -*-===//
+//===--- Projection.h - Utilities for working with Projections --*- C++ -*-===//
 //
 // This source file is part of the Swift.org open source project
 //
diff --git a/include/swift/SIL/SILInstruction.h b/include/swift/SIL/SILInstruction.h
index 0de6537d4713f..b2eeb96b190f8 100644
--- a/include/swift/SIL/SILInstruction.h
+++ b/include/swift/SIL/SILInstruction.h
@@ -960,7 +960,7 @@ class FunctionRefInst : public LiteralInst {
   /// Construct a FunctionRefInst.
   ///
   /// \param DebugLoc  The location of the reference.
-  /// \param F    The function being referenced.
+  /// \param F         The function being referenced.
   FunctionRefInst(SILDebugLocation *DebugLoc, SILFunction *F);
 
 public:
diff --git a/include/swift/SILOptimizer/Utils/Local.h b/include/swift/SILOptimizer/Utils/Local.h
index 5bc19e1a5cc1b..7606a55faf42f 100644
--- a/include/swift/SILOptimizer/Utils/Local.h
+++ b/include/swift/SILOptimizer/Utils/Local.h
@@ -434,7 +434,7 @@ class CastOptimizer {
       SILBasicBlock *SuccessBB,
       SILBasicBlock *FailureBB);
 
-  /// Optimize a cast from   a Swift type implementing _ObjectiveCBridgeable
+  /// Optimize a cast from a Swift type implementing _ObjectiveCBridgeable
   /// into a bridged ObjC type.
   SILInstruction *
   optimizeBridgedSwiftToObjCCast(SILInstruction *Inst,
diff --git a/lib/IDE/ReconstructType.cpp b/lib/IDE/ReconstructType.cpp
index 88d5a59bef84d..fa7f9bed46d7c 100644
--- a/lib/IDE/ReconstructType.cpp
+++ b/lib/IDE/ReconstructType.cpp
@@ -799,7 +799,7 @@ FindNamedDecls (SwiftASTContext *ast,
       }
     }
   }
-  else  if (result._module)
+  else if (result._module)
   {
     swift::Module::AccessPathTy access_path;
     llvm::SmallVector<swift::ValueDecl*, 4> decls;
diff --git a/lib/IRGen/GenObjC.cpp b/lib/IRGen/GenObjC.cpp
index 1ff9b27e7450f..4261935b02474 100644
--- a/lib/IRGen/GenObjC.cpp
+++ b/lib/IRGen/GenObjC.cpp
@@ -341,7 +341,7 @@ llvm::Constant *IRGenModule::getAddrOfObjCSelectorRef(StringRef selector) {
 
 /// Get or create an ObjC protocol record. Always returns an i8*. We lazily
 /// create ObjC protocol_t records for protocols, storing references to the
-/// record into the __objc_protolist and  and __objc_protorefs sections to be
+/// record into the __objc_protolist and __objc_protorefs sections to be
 /// fixed up by the runtime.
 ///
 /// It is not correct to use this value as a Protocol* reference directly. The
@@ -356,7 +356,7 @@ llvm::Constant *IRGenModule::getAddrOfObjCProtocolRecord(ProtocolDecl *proto,
 
 /// Get or create an ObjC protocol reference. Always returns an i8**. We lazily
 /// create ObjC protocol_t records for protocols, storing references to the
-/// record into the __objc_protolist and  and __objc_protorefs sections to be
+/// record into the __objc_protolist and __objc_protorefs sections to be
 /// fixed up by the runtime.
 llvm::Constant *IRGenModule::getAddrOfObjCProtocolRef(ProtocolDecl *proto,
                                                ForDefinition_t forDefinition) {
diff --git a/lib/IRGen/GenTuple.cpp b/lib/IRGen/GenTuple.cpp
index a62b5d8fc32ab..2d66368388460 100644
--- a/lib/IRGen/GenTuple.cpp
+++ b/lib/IRGen/GenTuple.cpp
@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 //
 //  This file implements IR generation for tuple types in Swift.  This
-//  includes creating the IR type as  well as emitting the primitive access
+//  includes creating the IR type as well as emitting the primitive access
 //  operations.
 //
 //  It is assumed in several places in IR-generation that the
diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index 02fea0ed2a09f..fe428b10e0278 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -4052,7 +4052,7 @@ Parser::parseDeclFunc(SourceLoc StaticLoc, StaticSpellingKind StaticSpelling,
   Identifier SimpleName;
   SourceLoc NameLoc = Tok.getLoc();
   Token NonglobalTok = Tok;
-  bool  NonglobalError = false;
+  bool NonglobalError = false;
 
   if (!(Flags & PD_AllowTopLevel) && 
       !(Flags & PD_InProtocol) &&
diff --git a/lib/SIL/SILInstruction.cpp b/lib/SIL/SILInstruction.cpp
index a0eff1a58173f..fefaed8638f63 100644
--- a/lib/SIL/SILInstruction.cpp
+++ b/lib/SIL/SILInstruction.cpp
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This file defines the high-level SILInstruction classes used for  SIL code.
+// This file defines the high-level SILInstruction classes used for SIL code.
 //
 //===----------------------------------------------------------------------===//
 
diff --git a/lib/SIL/SILInstructions.cpp b/lib/SIL/SILInstructions.cpp
index 56a622166bf03..7dd2e8c6c6d29 100644
--- a/lib/SIL/SILInstructions.cpp
+++ b/lib/SIL/SILInstructions.cpp
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This file defines the high-level SILInstruction classes used for  SIL code.
+// This file defines the high-level SILInstruction classes used for SIL code.
 //
 //===----------------------------------------------------------------------===//
 
diff --git a/lib/SILGen/SILGenApply.cpp b/lib/SILGen/SILGenApply.cpp
index 1bb6a92b8ce3a..dcb94b07342dd 100644
--- a/lib/SILGen/SILGenApply.cpp
+++ b/lib/SILGen/SILGenApply.cpp
@@ -3503,7 +3503,7 @@ namespace {
             closureTy);
           result = ManagedValue::forUnmanaged(partialApply);
        // Handle a regular call.
-       } else  if (!specializedEmitter) {
+       } else if (!specializedEmitter) {
           result = gen.emitApply(uncurriedLoc.getValue(), mv,
                                  callee.getSubstitutions(),
                                  uncurriedArgs,
diff --git a/lib/SILGen/SILGenFunction.h b/lib/SILGen/SILGenFunction.h
index 10c271b1c7306..ed4f9f7999041 100644
--- a/lib/SILGen/SILGenFunction.h
+++ b/lib/SILGen/SILGenFunction.h
@@ -568,7 +568,7 @@ class LLVM_LIBRARY_VISIBILITY SILGenFunction
                       SILDeclRef fromLevel, SILDeclRef toLevel);
   /// Generates a thunk from a foreign function to the native Swift convention.
   void emitForeignToNativeThunk(SILDeclRef thunk);
-  /// Generates a thunk from a native function to the  conventions.
+  /// Generates a thunk from a native function to the conventions.
   void emitNativeToForeignThunk(SILDeclRef thunk);
   
   // Generate a nullary function that returns the given value.
diff --git a/lib/SILOptimizer/Analysis/MemoryBehavior.cpp b/lib/SILOptimizer/Analysis/MemoryBehavior.cpp
index 909256a494a6f..a0dd7af3eb8c5 100644
--- a/lib/SILOptimizer/Analysis/MemoryBehavior.cpp
+++ b/lib/SILOptimizer/Analysis/MemoryBehavior.cpp
@@ -108,9 +108,9 @@ class MemoryBehaviorVisitor
 #define OPERANDALIAS_MEMBEHAVIOR_INST(Name)                             \
   MemBehavior visit##Name(Name *I) {                                    \
     for (Operand &Op : I->getAllOperands()) {                           \
-      if (!AA->isNoAlias(Op.get(), V)) {                                 \
+      if (!AA->isNoAlias(Op.get(), V)) {                                \
         DEBUG(llvm::dbgs() << "  " #Name                                \
-              " does alias inst. Returning  Normal behavior.\n");       \
+              " does alias inst. Returning Normal behavior.\n");        \
         return I->getMemoryBehavior();                                  \
       }                                                                 \
     }                                                                   \
diff --git a/lib/SILOptimizer/Mandatory/DefiniteInitialization.cpp b/lib/SILOptimizer/Mandatory/DefiniteInitialization.cpp
index 26a30671ceec9..c53ac56cecb5e 100644
--- a/lib/SILOptimizer/Mandatory/DefiniteInitialization.cpp
+++ b/lib/SILOptimizer/Mandatory/DefiniteInitialization.cpp
@@ -1701,7 +1701,7 @@ void LifetimeChecker::deleteDeadRelease(unsigned ReleaseID) {
 
 /// processNonTrivialRelease - We handle two kinds of release instructions here:
 /// destroy_addr for alloc_stack's and strong_release/dealloc_box for
-/// alloc_box's.  By the  time that DI gets here, we've validated that all uses
+/// alloc_box's.  By the time that DI gets here, we've validated that all uses
 /// of the memory location are valid.  Unfortunately, the uses being valid
 /// doesn't mean that the memory is actually initialized on all paths leading to
 /// a release.  As such, we have to push the releases up the CFG to where the
diff --git a/lib/SILOptimizer/Mandatory/PredictableMemOpt.cpp b/lib/SILOptimizer/Mandatory/PredictableMemOpt.cpp
index 558ee452d148a..b05a38eb05038 100644
--- a/lib/SILOptimizer/Mandatory/PredictableMemOpt.cpp
+++ b/lib/SILOptimizer/Mandatory/PredictableMemOpt.cpp
@@ -925,7 +925,7 @@ bool AllocOptimize::tryToRemoveDeadAllocation() {
 bool AllocOptimize::doIt() {
   bool Changed = false;
 
-  // Don't  try to optimize incomplete aggregates.
+  // Don't try to optimize incomplete aggregates.
   if (MemoryType.aggregateHasUnreferenceableStorage())
     return false;
 
diff --git a/lib/SILOptimizer/SILCombiner/SILCombinerApplyVisitors.cpp b/lib/SILOptimizer/SILCombiner/SILCombinerApplyVisitors.cpp
index 678c53d902490..16058a0904f47 100644
--- a/lib/SILOptimizer/SILCombiner/SILCombinerApplyVisitors.cpp
+++ b/lib/SILOptimizer/SILCombiner/SILCombinerApplyVisitors.cpp
@@ -624,7 +624,7 @@ static SILValue getInitOrOpenExistential(AllocStackInst *ASI, SILValue &Src) {
   return SrcValue;
 }
 
-/// find the init_existential, which could be used to  determine a concrete
+/// find the init_existential, which could be used to determine a concrete
 /// type of the \p Self.
 static SILInstruction *findInitExistential(FullApplySite AI, SILValue Self,
                                            CanType &OpenedArchetype) {
@@ -1015,7 +1015,7 @@ static ApplyInst *optimizeCastThroughThinFunctionPointer(
     return nullptr;
 
   // The fourth parameter is a metatype of a bound generic type. Use it to
-  // obtain  the type substitutions to apply.
+  // obtain the type substitutions to apply.
   auto MetaTy = dyn_cast<MetatypeType>(CastedParams[3].getType());
   if (!MetaTy)
     return nullptr;
diff --git a/lib/SILOptimizer/Transforms/DeadStoreElimination.cpp b/lib/SILOptimizer/Transforms/DeadStoreElimination.cpp
index 5c3ee23055614..c1f25f4abc2fa 100644
--- a/lib/SILOptimizer/Transforms/DeadStoreElimination.cpp
+++ b/lib/SILOptimizer/Transforms/DeadStoreElimination.cpp
@@ -178,7 +178,7 @@ class DSEContext;
 /// 2. When a load instruction is encountered, remove the loaded location and
 ///    any location it may alias with from the BBWriteSetMid.
 ///
-/// 3. When an instruction reads from  memory in an unknown way, the
+/// 3. When an instruction reads from memory in an unknown way, the
 ///    BBWriteSetMid bit is cleared if the instruction can read the
 ///    corresponding LSLocation.
 ///
diff --git a/lib/SILOptimizer/Transforms/RedundantOverflowCheckRemoval.cpp b/lib/SILOptimizer/Transforms/RedundantOverflowCheckRemoval.cpp
index bf9207c2af57e..a87971a28582e 100644
--- a/lib/SILOptimizer/Transforms/RedundantOverflowCheckRemoval.cpp
+++ b/lib/SILOptimizer/Transforms/RedundantOverflowCheckRemoval.cpp
@@ -232,7 +232,7 @@ class RedundantOverflowCheckRemovalPass : public SILFunctionTransform {
   static bool isKnownPositive(SILValue N) {
     if (IntegerLiteralInst *NI = dyn_cast<IntegerLiteralInst>(N))
       return NI->getValue().isStrictlyPositive();
-    return  false;
+    return false;
   }
 
   /// Return true if the absolute value of \p A is smaller than the
@@ -278,7 +278,7 @@ class RedundantOverflowCheckRemovalPass : public SILFunctionTransform {
         if (F.Relationship == ValueRelation::SAdd) {
           // L + R already known to not trap at this point in the program.
           // And the following applies:
-          // L >= A and R >= B  or (commutatively) R >= A and L >= B.
+          // L >= A and R >= B or (commutatively) R >= A and L >= B.
           SILValue A = BI->getOperand(0);
           SILValue B = BI->getOperand(1);
           if (knownRelation(A, L,  ValueRelation::SLE) &&
@@ -307,7 +307,7 @@ class RedundantOverflowCheckRemovalPass : public SILFunctionTransform {
         if (F.Relationship == ValueRelation::UAdd) {
           // L + R already known to not trap at this point in the program.
           // And the following applies:
-          // L >= A and R >= B  or (commutatively) R >= A and L >= B.
+          // L >= A and R >= B or (commutatively) R >= A and L >= B.
           SILValue A = BI->getOperand(0);
           SILValue B = BI->getOperand(1);
           if (knownRelation(A, L,  ValueRelation::ULE) &&
@@ -368,7 +368,7 @@ class RedundantOverflowCheckRemovalPass : public SILFunctionTransform {
         if (F.Relationship == ValueRelation::UMul) {
           // L * R already known to not trap at this point in the program.
           // And the following applies:
-          // L >= A and R >= B  or (commutatively) R >= A and L >= B.
+          // L >= A and R >= B or (commutatively) R >= A and L >= B.
           SILValue A = BI->getOperand(0);
           SILValue B = BI->getOperand(1);
           if (knownRelation(A, L,  ValueRelation::ULE) &&
@@ -526,7 +526,7 @@ class RedundantOverflowCheckRemovalPass : public SILFunctionTransform {
     ValueRelation Rel;
     switch (BI->getBuiltinInfo().ID) {
       default: return;
-      case  BuiltinValueKind::SAddOver:
+      case BuiltinValueKind::SAddOver:
         Rel = ValueRelation::SAdd;
         break;
       case BuiltinValueKind::UAddOver:
diff --git a/lib/SILOptimizer/Transforms/SILCodeMotion.cpp b/lib/SILOptimizer/Transforms/SILCodeMotion.cpp
index 22c436174bf58..c7189d675697d 100644
--- a/lib/SILOptimizer/Transforms/SILCodeMotion.cpp
+++ b/lib/SILOptimizer/Transforms/SILCodeMotion.cpp
@@ -896,7 +896,7 @@ static bool isRetainAvailableInSomeButNotAllPredecessors(
         });
 
     // Check that there is no decrement or check from the increment to the end
-    // of the basic block. After we have hoisted the first release  this release
+    // of the basic block. After we have hoisted the first release this release
     // would prevent further hoisting. Instead we check that no decrement or
     // check occurs up to this hoisted release.
     auto End = CheckUpToInstruction[Pred];
diff --git a/lib/SILOptimizer/Transforms/SILLowerAggregateInstrs.cpp b/lib/SILOptimizer/Transforms/SILLowerAggregateInstrs.cpp
index d1780e2e2e610..534cc592c8931 100644
--- a/lib/SILOptimizer/Transforms/SILLowerAggregateInstrs.cpp
+++ b/lib/SILOptimizer/Transforms/SILLowerAggregateInstrs.cpp
@@ -156,7 +156,7 @@ static bool expandDestroyAddr(DestroyAddrInst *DA) {
 
 static bool expandReleaseValue(ReleaseValueInst *DV) {
   SILModule &Module = DV->getModule();
-  SILBuilderWithScope  Builder(DV);
+  SILBuilderWithScope Builder(DV);
 
   // Strength reduce destroy_addr inst into release/store if
   // we have a non-address only type.
diff --git a/lib/SILOptimizer/Utils/CheckedCastBrJumpThreading.cpp b/lib/SILOptimizer/Utils/CheckedCastBrJumpThreading.cpp
index 33a67007317e3..7b5b536ca4c2d 100644
--- a/lib/SILOptimizer/Utils/CheckedCastBrJumpThreading.cpp
+++ b/lib/SILOptimizer/Utils/CheckedCastBrJumpThreading.cpp
@@ -537,7 +537,7 @@ bool CheckedCastBrJumpThreading::areEquivalentConditionsAlongSomePaths() {
 }
 
 /// Check if conditions of CCBI and DomCCBI are equivalent along
-/// all or at least  some paths.
+/// all or at least some paths.
 bool CheckedCastBrJumpThreading::areEquivalentConditionsAlongPaths() {
   // Are conditions equivalent along all paths?
   if (DomCondition == Condition) {
diff --git a/lib/SILOptimizer/Utils/Devirtualize.cpp b/lib/SILOptimizer/Utils/Devirtualize.cpp
index bbfb91eb5acb9..61fccf2c7d085 100644
--- a/lib/SILOptimizer/Utils/Devirtualize.cpp
+++ b/lib/SILOptimizer/Utils/Devirtualize.cpp
@@ -694,7 +694,7 @@ static ApplySite devirtualizeWitnessMethod(ApplySite AI, SILFunction *F,
   // Collect all the required substitutions.
   //
   // The complete set of substitutions may be different, e.g. because the found
-  // witness thunk F may have been created by a  specialization pass and have
+  // witness thunk F may have been created by a specialization pass and have
   // additional generic parameters.
   SmallVector<Substitution, 16> NewSubstList(Subs.begin(), Subs.end());
   if (auto generics = AI.getOrigCalleeType()->getGenericSignature()) {
diff --git a/lib/SILOptimizer/Utils/Local.cpp b/lib/SILOptimizer/Utils/Local.cpp
index 322b4a65c8ee2..3268b8c48c1f2 100644
--- a/lib/SILOptimizer/Utils/Local.cpp
+++ b/lib/SILOptimizer/Utils/Local.cpp
@@ -1120,7 +1120,7 @@ ValueLifetime ValueLifetimeAnalysis::computeLastUsers() {
 //                    Casts Optimization and Simplification
 //===----------------------------------------------------------------------===//
 
-/// \brief  Get a substitution corresponding to the type witness.
+/// \brief Get a substitution corresponding to the type witness.
 /// Inspired by ProtocolConformance::getTypeWitnessByName.
 static const Substitution *
 getTypeWitnessByName(ProtocolConformance *conformance, Identifier name) {
@@ -1187,7 +1187,7 @@ optimizeBridgedObjCToSwiftCast(SILInstruction *Inst,
   auto Loc = Inst->getLoc();
 
   // The conformance to _BridgedToObjectiveC is statically known.
-  // Retrieve the  bridging operation to be used if a static conformance
+  // Retrieve the bridging operation to be used if a static conformance
   // to _BridgedToObjectiveC can be proven.
   FuncDecl *BridgeFuncDecl =
       isConditional
diff --git a/lib/Sema/CSApply.cpp b/lib/Sema/CSApply.cpp
index f457c2bc986e5..6c1d49ebf5aca 100644
--- a/lib/Sema/CSApply.cpp
+++ b/lib/Sema/CSApply.cpp
@@ -30,7 +30,7 @@
 using namespace swift;
 using namespace constraints;
 
-/// \brief  Get a substitution corresponding to the type witness.
+/// \brief Get a substitution corresponding to the type witness.
 /// Inspired by ProtocolConformance::getTypeWitnessByName.
 const Substitution *
 getTypeWitnessByName(ProtocolConformance *conformance,
@@ -1348,13 +1348,13 @@ namespace {
 
       if (conformsToBridgedToObjectiveC) {
         // The conformance to _BridgedToObjectiveC is statically known.
-        // Retrieve the  bridging operation to be used if a static conformance
+        // Retrieve the bridging operation to be used if a static conformance
         // to _BridgedToObjectiveC can be proven.
         fn = conditional
                  ? tc.Context.getConditionallyBridgeFromObjectiveCBridgeable(&tc)
                  : tc.Context.getForceBridgeFromObjectiveCBridgeable(&tc);
       } else {
-        // Retrieve the  bridging operation to be used if a static conformance
+        // Retrieve the bridging operation to be used if a static conformance
         // to _BridgedToObjectiveC cannot be proven.
         fn = conditional ? tc.Context.getConditionallyBridgeFromObjectiveC(&tc)
                          : tc.Context.getForceBridgeFromObjectiveC(&tc);
diff --git a/lib/Sema/DerivedConformances.cpp b/lib/Sema/DerivedConformances.cpp
index e0f6e9e2ebb40..fdf813d0ed32b 100644
--- a/lib/Sema/DerivedConformances.cpp
+++ b/lib/Sema/DerivedConformances.cpp
@@ -40,7 +40,7 @@ ValueDecl *DerivedConformance::getDerivableRequirement(NominalTypeDecl *nominal,
 
     // Retrieve the requirement.
     auto results = proto->lookupDirect(name);
-    return  results.empty() ? nullptr : results.front();
+    return results.empty() ? nullptr : results.front();
   };
 
   // Properties.
diff --git a/lib/Sema/TypeCheckDecl.cpp b/lib/Sema/TypeCheckDecl.cpp
index 51461155bee54..182bc323c5a32 100644
--- a/lib/Sema/TypeCheckDecl.cpp
+++ b/lib/Sema/TypeCheckDecl.cpp
@@ -4814,7 +4814,7 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
     return true;
   }
 
-  /// Returns true if a  diagnostic about an accessor being less available
+  /// Returns true if a diagnostic about an accessor being less available
   /// than the accessor it overrides would be redundant because we will
   /// already emit another diagnostic.
   static bool
diff --git a/lib/Sema/TypeChecker.cpp b/lib/Sema/TypeChecker.cpp
index b80830aabd04c..ed829723d18ba 100644
--- a/lib/Sema/TypeChecker.cpp
+++ b/lib/Sema/TypeChecker.cpp
@@ -1804,7 +1804,7 @@ static const Decl *ancestorTypeLevelDeclForAvailabilityFixit(const Decl *D) {
 /// declaration context containing the reference, make a best effort find up to
 /// three locations for potential fixits.
 ///
-/// \param  FoundVersionCheckNode Returns a node that can be wrapped in a
+/// \param FoundVersionCheckNode Returns a node that can be wrapped in a
 /// if #available(...) { ... } version check to fix the unavailable reference,
 /// or None if such a node cannot be found.
 ///
diff --git a/stdlib/public/core/String.swift b/stdlib/public/core/String.swift
index b1cd66211de02..d0a6a65935d12 100644
--- a/stdlib/public/core/String.swift
+++ b/stdlib/public/core/String.swift
@@ -306,7 +306,7 @@ extension String {
 /// - returns:
 ///   * an unspecified value less than zero if `lhs < rhs`,
 ///   * zero if `lhs == rhs`,
-///   * an unspecified value greater than zero  if `lhs > rhs`.
+///   * an unspecified value greater than zero if `lhs > rhs`.
 @_silgen_name("swift_stdlib_compareNSStringDeterministicUnicodeCollation")
 public func _stdlib_compareNSStringDeterministicUnicodeCollation(
   lhs: AnyObject, _ rhs: AnyObject
diff --git a/tools/SourceKit/lib/Support/FuzzyStringMatcher.cpp b/tools/SourceKit/lib/Support/FuzzyStringMatcher.cpp
index 1ccd03f08b940..a6bc6f9089d80 100644
--- a/tools/SourceKit/lib/Support/FuzzyStringMatcher.cpp
+++ b/tools/SourceKit/lib/Support/FuzzyStringMatcher.cpp
@@ -35,7 +35,7 @@ FuzzyStringMatcher::FuzzyStringMatcher(StringRef pattern_)
   assert(pattern.size() == lowercasePattern.size());
 
   // FIXME: pull out the magic constants.
-  // This depends on the inner details of the matching algorithm and  will need
+  // This depends on the inner details of the matching algorithm and will need
   // to be updated if we substantially alter it.
   if (pattern.size() == 1) {
     maxScore = 3.0 +  // uppercase match
diff --git a/tools/SourceKit/tools/sourcekitd/include/sourcekitd/sourcekitd.h b/tools/SourceKit/tools/sourcekitd/include/sourcekitd/sourcekitd.h
index 35e5cb92bbe5b..714817bffdb4c 100644
--- a/tools/SourceKit/tools/sourcekitd/include/sourcekitd/sourcekitd.h
+++ b/tools/SourceKit/tools/sourcekitd/include/sourcekitd/sourcekitd.h
@@ -151,7 +151,7 @@ SOURCEKITD_PUBLIC SOURCEKITD_NONNULL1 SOURCEKITD_WARN_RESULT
 sourcekitd_uid_t
 sourcekitd_uid_get_from_buf(const char *buf, size_t length);
 
-/// \brief Get the length of the string associated with  a \c sourcekitd_uid_t.
+/// \brief Get the length of the string associated with a \c sourcekitd_uid_t.
 SOURCEKITD_PUBLIC SOURCEKITD_NONNULL1 SOURCEKITD_WARN_RESULT
 size_t
 sourcekitd_uid_get_length(sourcekitd_uid_t obj);
diff --git a/tools/SourceKit/tools/sourcekitd/lib/API/Requests.cpp b/tools/SourceKit/tools/sourcekitd/lib/API/Requests.cpp
index ce1801a749fc2..20b4a33901e86 100644
--- a/tools/SourceKit/tools/sourcekitd/lib/API/Requests.cpp
+++ b/tools/SourceKit/tools/sourcekitd/lib/API/Requests.cpp
@@ -1754,7 +1754,7 @@ bool SKEditorConsumer::handleDocumentSubStructureElement(UIdent Kind,
   Node.set(KeyKind, Kind);
   Node.set(KeyOffset, Offset);
   Node.set(KeyLength, Length);
-  return  true;
+  return true;
 }
 
 bool SKEditorConsumer::recordAffectedRange(unsigned Offset, unsigned Length) {
diff --git a/utils/swift-project-settings.el b/utils/swift-project-settings.el
index 9ab3fe62bb204..f94fc1f5831c6 100644
--- a/utils/swift-project-settings.el
+++ b/utils/swift-project-settings.el
@@ -198,7 +198,7 @@ Swift header should look like.
   ;; is non-empty, v1 all over again
   '(setq v2
          (replace-regexp-in-string "\\` +" ""
-          (if (and comment-end (> (length comment-end) 0)) comment-end  v1)))
+          (if (and comment-end (> (length comment-end) 0)) comment-end v1)))
   
   v1 "===--- "
   str & " " | -1
diff --git a/utils/vim/syntax/sil.vim b/utils/vim/syntax/sil.vim
index a29810aa1a9da..c927345f71664 100644
--- a/utils/vim/syntax/sil.vim
+++ b/utils/vim/syntax/sil.vim
@@ -27,7 +27,7 @@ syn keyword swiftKeyword public hidden private shared public_external hidden_ext
 syn keyword swiftKeyword getter setter allocator initializer enumelt destroyer globalaccessor objc skipwhite
 syn keyword swiftKeyword alloc_stack alloc_ref alloc_ref_dynamic alloc_box dealloc_stack dealloc_box dealloc_ref skipwhite
 syn keyword swiftKeyword debug_value debug_value_addr skipwhite
-syn keyword swiftKeyword load store assign  mark_uninitialized mark_function_escape copy_addr destroy_addr index_addr index_raw_pointer to skipwhite
+syn keyword swiftKeyword load store assign mark_uninitialized mark_function_escape copy_addr destroy_addr index_addr index_raw_pointer to skipwhite
 syn keyword swiftKeyword strong_retain strong_release strong_retain_unowned ref_to_unowned unowned_to_ref unowned_retain unowned_release load_weak store_weak fix_lifetime skipwhite
 syn keyword swiftKeyword function_ref integer_literal float_literal string_literal global_addr skipwhite
 syn keyword swiftKeyword class_method super_method witness_method dynamic_method skipwhite