diff --git a/include/swift/AST/DiagnosticsFrontend.def b/include/swift/AST/DiagnosticsFrontend.def
index 387106b5c1a53..8bde9406a757d 100644
--- a/include/swift/AST/DiagnosticsFrontend.def
+++ b/include/swift/AST/DiagnosticsFrontend.def
@@ -61,6 +61,10 @@ ERROR(error_unsupported_target_arch, none,
 ERROR(error_unsupported_opt_for_target, none,
       "unsupported option '%0' for target '%1'", (StringRef, StringRef))
 
+WARNING(warning_inferred_simulator_target,none,
+      "inferring simulator environment for target '%0'; "
+      "use '-target %1' instead", (StringRef, StringRef))
+
 ERROR(error_argument_not_allowed_with, none,
       "argument '%0' is not allowed with '%1'", (StringRef, StringRef))
 
diff --git a/include/swift/Basic/Platform.h b/include/swift/Basic/Platform.h
index eb21ea7a29714..c0cd0fa832eef 100644
--- a/include/swift/Basic/Platform.h
+++ b/include/swift/Basic/Platform.h
@@ -43,12 +43,12 @@ namespace swift {
   /// Returns true if the given triple represents watchOS running in a simulator.
   bool tripleIsWatchSimulator(const llvm::Triple &triple);
 
-  /// Return true if the given triple represents any simulator.
-  bool tripleIsAnySimulator(const llvm::Triple &triple);
-
   /// Returns true if the given triple represents a macCatalyst environment.
   bool tripleIsMacCatalystEnvironment(const llvm::Triple &triple);
 
+  /// Determine whether the triple infers the "simulator" environment.
+  bool tripleInfersSimulatorEnvironment(const llvm::Triple &triple);
+
   /// Returns true if the given -target triple and -target-variant triple
   /// can be zippered.
   bool triplesAreValidForZippering(const llvm::Triple &target,
diff --git a/lib/Basic/LangOptions.cpp b/lib/Basic/LangOptions.cpp
index 682f6e1010c61..cc2bf058d14f2 100644
--- a/lib/Basic/LangOptions.cpp
+++ b/lib/Basic/LangOptions.cpp
@@ -361,7 +361,7 @@ std::pair<bool, bool> LangOptions::setTarget(llvm::Triple triple) {
   // Set the "targetEnvironment" platform condition if targeting a simulator
   // environment. Otherwise _no_ value is present for targetEnvironment; it's
   // an optional disambiguating refinement of the triple.
-  if (swift::tripleIsAnySimulator(Target))
+  if (Target.isSimulatorEnvironment())
     addPlatformConditionValue(PlatformConditionKind::TargetEnvironment,
                               "simulator");
 
diff --git a/lib/Basic/Platform.cpp b/lib/Basic/Platform.cpp
index 5f59d5a756421..5ce96b8f5e82d 100644
--- a/lib/Basic/Platform.cpp
+++ b/lib/Basic/Platform.cpp
@@ -19,40 +19,17 @@
 using namespace swift;
 
 bool swift::tripleIsiOSSimulator(const llvm::Triple &triple) {
-  llvm::Triple::ArchType arch = triple.getArch();
   return (triple.isiOS() &&
           !tripleIsMacCatalystEnvironment(triple) &&
-          // FIXME: transitional, this should eventually stop testing arch, and
-          // switch to only checking the -environment field.
-          (triple.isSimulatorEnvironment() ||
-           arch == llvm::Triple::x86 || arch == llvm::Triple::x86_64));
+          triple.isSimulatorEnvironment());
 }
 
 bool swift::tripleIsAppleTVSimulator(const llvm::Triple &triple) {
-  llvm::Triple::ArchType arch = triple.getArch();
-  return (triple.isTvOS() &&
-          // FIXME: transitional, this should eventually stop testing arch, and
-          // switch to only checking the -environment field.
-          (triple.isSimulatorEnvironment() ||
-           arch == llvm::Triple::x86 || arch == llvm::Triple::x86_64));
+  return (triple.isTvOS() && triple.isSimulatorEnvironment());
 }
 
 bool swift::tripleIsWatchSimulator(const llvm::Triple &triple) {
-  llvm::Triple::ArchType arch = triple.getArch();
-  return (triple.isWatchOS() &&
-          // FIXME: transitional, this should eventually stop testing arch, and
-          // switch to only checking the -environment field.
-          (triple.isSimulatorEnvironment() ||
-           arch == llvm::Triple::x86 || arch == llvm::Triple::x86_64));
-}
-
-bool swift::tripleIsAnySimulator(const llvm::Triple &triple) {
-  // FIXME: transitional, this should eventually just use the -environment
-  // field.
-  return triple.isSimulatorEnvironment() ||
-    tripleIsiOSSimulator(triple) ||
-    tripleIsWatchSimulator(triple) ||
-    tripleIsAppleTVSimulator(triple);
+  return (triple.isWatchOS() && triple.isSimulatorEnvironment());
 }
 
 bool swift::tripleIsMacCatalystEnvironment(const llvm::Triple &triple) {
@@ -60,6 +37,21 @@ bool swift::tripleIsMacCatalystEnvironment(const llvm::Triple &triple) {
       triple.getEnvironment() == llvm::Triple::MacABI;
 }
 
+bool swift::tripleInfersSimulatorEnvironment(const llvm::Triple &triple) {
+  switch (triple.getOS()) {
+  case llvm::Triple::IOS:
+  case llvm::Triple::TvOS:
+  case llvm::Triple::WatchOS:
+    return !triple.hasEnvironment() &&
+        (triple.getArch() == llvm::Triple::x86 ||
+         triple.getArch() == llvm::Triple::x86_64) &&
+        !tripleIsMacCatalystEnvironment(triple);
+
+  default:
+    return false;
+  }
+}
+
 bool swift::triplesAreValidForZippering(const llvm::Triple &target,
                                         const llvm::Triple &targetVariant) {
   // The arch and vendor must match.
@@ -327,14 +319,6 @@ getOSForAppleTargetSpecificModuleTriple(const llvm::Triple &triple) {
 static Optional<StringRef>
 getEnvironmentForAppleTargetSpecificModuleTriple(const llvm::Triple &triple) {
   auto tripleEnvironment = triple.getEnvironmentName();
-
-  // If the environment is empty, infer a "simulator" environment based on the
-  // OS and architecture combination. This feature is deprecated and exists for
-  // backwards compatibility only; build systems should pass the "simulator"
-  // environment explicitly if they know they're building for a simulator.
-  if (tripleEnvironment == "" && swift::tripleIsAnySimulator(triple))
-    return StringRef("simulator");
-
   return llvm::StringSwitch<Optional<StringRef>>(tripleEnvironment)
               .Cases("unknown", "", None)
   // These values are also supported, but are handled by the default case below:
diff --git a/lib/Driver/DarwinToolChains.cpp b/lib/Driver/DarwinToolChains.cpp
index 7681ef5960dec..b13661acd27ee 100644
--- a/lib/Driver/DarwinToolChains.cpp
+++ b/lib/Driver/DarwinToolChains.cpp
@@ -465,7 +465,7 @@ toolchains::Darwin::addProfileGenerationArgs(ArgStringList &Arguments,
     }
 
     StringRef Sim;
-    if (tripleIsAnySimulator(Triple)) {
+    if (Triple.isSimulatorEnvironment()) {
       Sim = "sim";
     }
 
diff --git a/lib/Driver/Driver.cpp b/lib/Driver/Driver.cpp
index d4a3d145e3e82..6b77c0f002fc6 100644
--- a/lib/Driver/Driver.cpp
+++ b/lib/Driver/Driver.cpp
@@ -264,17 +264,31 @@ static void validateArgs(DiagnosticEngine &diags, const ArgList &args,
 std::unique_ptr<ToolChain>
 Driver::buildToolChain(const llvm::opt::InputArgList &ArgList) {
 
-  if (const Arg *A = ArgList.getLastArg(options::OPT_target))
+  if (const Arg *A = ArgList.getLastArg(options::OPT_target)) {
     DefaultTargetTriple = llvm::Triple::normalize(A->getValue());
+  }
+
+  llvm::Triple target(DefaultTargetTriple);
 
-  const llvm::Triple target(DefaultTargetTriple);
+  // Backward compatibility hack: infer "simulator" environment for x86
+  // iOS/tvOS/watchOS.
+  if (tripleInfersSimulatorEnvironment(target)) {
+    // Set the simulator environment.
+    target.setEnvironment(llvm::Triple::EnvironmentType::Simulator);
+
+    auto newTargetTriple = target.normalize();
+    Diags.diagnose(SourceLoc(), diag::warning_inferred_simulator_target,
+                   DefaultTargetTriple, newTargetTriple);
+
+    DefaultTargetTriple = newTargetTriple;
+  }
 
   switch (target.getOS()) {
-  case llvm::Triple::Darwin:
-  case llvm::Triple::MacOSX:
   case llvm::Triple::IOS:
   case llvm::Triple::TvOS:
-  case llvm::Triple::WatchOS: {
+  case llvm::Triple::WatchOS:
+  case llvm::Triple::Darwin:
+  case llvm::Triple::MacOSX: {
     Optional<llvm::Triple> targetVariant;
     if (const Arg *A = ArgList.getLastArg(options::OPT_target_variant))
       targetVariant = llvm::Triple(llvm::Triple::normalize(A->getValue()));
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index fcdfd88dbce70..1bc3bdf635578 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -553,9 +553,22 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
 
   llvm::Triple Target = Opts.Target;
   StringRef TargetArg;
+  std::string TargetArgScratch;
+
   if (const Arg *A = Args.getLastArg(OPT_target)) {
     Target = llvm::Triple(A->getValue());
     TargetArg = A->getValue();
+
+    // Backward compatibility hack: infer "simulator" environment for x86
+    // iOS/tvOS/watchOS. The driver takes care of this for the frontend
+    // most of the time, but loading of old .swiftinterface files goes
+    // directly to the frontend.
+    if (tripleInfersSimulatorEnvironment(Target)) {
+      // Set the simulator environment.
+      Target.setEnvironment(llvm::Triple::EnvironmentType::Simulator);
+      TargetArgScratch = Target.str();
+      TargetArg = TargetArgScratch;
+    }
   }
 
   if (const Arg *A = Args.getLastArg(OPT_target_variant)) {
diff --git a/lib/IRGen/SwiftTargetInfo.cpp b/lib/IRGen/SwiftTargetInfo.cpp
index a7b6f84bf06c0..a5e435d433973 100644
--- a/lib/IRGen/SwiftTargetInfo.cpp
+++ b/lib/IRGen/SwiftTargetInfo.cpp
@@ -69,7 +69,7 @@ static void configureX86_64(IRGenModule &IGM, const llvm::Triple &triple,
             SWIFT_ABI_X86_64_SWIFT_SPARE_BITS_MASK);
   setToMask(target.IsObjCPointerBit, 64, SWIFT_ABI_X86_64_IS_OBJC_BIT);
 
-  if (tripleIsAnySimulator(triple)) {
+  if (triple.isSimulatorEnvironment()) {
     setToMask(target.ObjCPointerReservedBits, 64,
               SWIFT_ABI_X86_64_SIMULATOR_OBJC_RESERVED_BITS_MASK);
   } else {
diff --git a/lib/Serialization/ModuleFile.cpp b/lib/Serialization/ModuleFile.cpp
index 7459fc76e217f..5b9c49019fbb8 100644
--- a/lib/Serialization/ModuleFile.cpp
+++ b/lib/Serialization/ModuleFile.cpp
@@ -1340,6 +1340,9 @@ static bool areCompatibleArchitectures(const llvm::Triple &moduleTarget,
 
 static bool areCompatibleOSs(const llvm::Triple &moduleTarget,
                              const llvm::Triple &ctxTarget) {
+  if (moduleTarget.getEnvironment() != ctxTarget.getEnvironment())
+    return false;
+
   if (moduleTarget.getOS() == ctxTarget.getOS())
     return true;
 
diff --git a/test/Driver/infer-simulator.swift b/test/Driver/infer-simulator.swift
new file mode 100644
index 0000000000000..8cdf9f82725c8
--- /dev/null
+++ b/test/Driver/infer-simulator.swift
@@ -0,0 +1,13 @@
+// Test the inference of the "simulator" environment within the driver.
+
+// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-ios11.0 %s > %t.simple.txt 2>&1
+// RUN: %FileCheck -check-prefix WARN_IOS_SIMULATOR %s < %t.simple.txt
+// WARN_IOS_SIMULATOR:  warning: inferring simulator environment for target 'x86_64-apple-ios11.0'; use '-target x86_64-apple-ios11.0-simulator' instead
+
+// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-tvos10.0 %s > %t.simple.txt 2>&1
+// RUN: %FileCheck -check-prefix WARN_TVOS_SIMULATOR %s < %t.simple.txt
+// WARN_TVOS_SIMULATOR: inferring simulator environment for target 'x86_64-apple-tvos10.0'; use '-target x86_64-apple-tvos10.0-simulator' instead
+
+// RUN: %swiftc_driver -driver-print-jobs -target i386-apple-watchos4.0 %s > %t.simple.txt 2>&1
+// RUN: %FileCheck -check-prefix WARN_WATCHOS_SIMULATOR %s < %t.simple.txt
+// WARN_WATCHOS_SIMULATOR: warning: inferring simulator environment for target 'i386-apple-watchos4.0'; use '-target i386-apple-watchos4.0-simulator' instead
diff --git a/test/Driver/linker-arclite.swift b/test/Driver/linker-arclite.swift
index c320f9b871de5..1ffc63c46ebe3 100644
--- a/test/Driver/linker-arclite.swift
+++ b/test/Driver/linker-arclite.swift
@@ -9,7 +9,7 @@
 // CHECK-SAME: -o {{[^ ]+}}
 
 
-// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-ios8.0 %S/../Inputs/empty.swift | %FileCheck -check-prefix IOS_ARCLITE %s
+// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-ios8.0-simulator %S/../Inputs/empty.swift | %FileCheck -check-prefix IOS_ARCLITE %s
 
 // IOS_ARCLITE: bin/ld{{"? }}
 // IOS_ARCLITE: -force_load {{[^ ]+/lib/arc/libarclite_iphonesimulator.a}}
@@ -18,8 +18,8 @@
 
 // RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-macosx10.11 %S/../Inputs/empty.swift | %FileCheck -check-prefix NO_ARCLITE %s
 // RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-macosx10.10 %S/../Inputs/empty.swift | %FileCheck -check-prefix ANY_ARCLITE %s
-// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-ios9 %S/../Inputs/empty.swift | %FileCheck -check-prefix NO_ARCLITE %s
-// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-ios8 %S/../Inputs/empty.swift | %FileCheck -check-prefix ANY_ARCLITE %s
+// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-ios9-simulator %S/../Inputs/empty.swift | %FileCheck -check-prefix NO_ARCLITE %s
+// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-ios8-simulator %S/../Inputs/empty.swift | %FileCheck -check-prefix ANY_ARCLITE %s
 // RUN: %swiftc_driver -driver-print-jobs -target arm64-apple-tvos9 %S/../Inputs/empty.swift | %FileCheck -check-prefix NO_ARCLITE %s
 // RUN: %swiftc_driver -driver-print-jobs -target armv7k-apple-watchos2 %S/../Inputs/empty.swift | %FileCheck -check-prefix NO_ARCLITE %s
 
diff --git a/test/Driver/linker.swift b/test/Driver/linker.swift
index 8e5017922f1d2..1c47aa6f420cd 100644
--- a/test/Driver/linker.swift
+++ b/test/Driver/linker.swift
@@ -6,13 +6,13 @@
 
 // RUN: not %swiftc_driver -driver-print-jobs -target x86_64-apple-macosx10.9 -static-stdlib %s 2>&1 | %FileCheck -check-prefix=SIMPLE_STATIC %s
 
-// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-ios7.1 %s 2>&1 > %t.simple.txt
+// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-ios7.1-simulator %s 2>&1 > %t.simple.txt
 // RUN: %FileCheck -check-prefix IOS_SIMPLE %s < %t.simple.txt
 
-// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-tvos9.0 %s 2>&1 > %t.simple.txt
+// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-tvos9.0-simulator %s 2>&1 > %t.simple.txt
 // RUN: %FileCheck -check-prefix tvOS_SIMPLE %s < %t.simple.txt
 
-// RUN: %swiftc_driver -driver-print-jobs -target i386-apple-watchos2.0 %s 2>&1 > %t.simple.txt
+// RUN: %swiftc_driver -driver-print-jobs -target i386-apple-watchos2.0-simulator %s 2>&1 > %t.simple.txt
 // RUN: %FileCheck -check-prefix watchOS_SIMPLE %s < %t.simple.txt
 
 // RUN: %swiftc_driver -driver-print-jobs -target x86_64-unknown-linux-gnu -Ffoo -Fsystem car -F cdr -framework bar -Lbaz -lboo -Xlinker -undefined %s 2>&1 > %t.linux.txt
@@ -47,7 +47,7 @@
 // RUN: %FileCheck %s < %t.complex.txt
 // RUN: %FileCheck -check-prefix COMPLEX %s < %t.complex.txt
 
-// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-ios7.1 -Xlinker -rpath -Xlinker customrpath -L foo %s 2>&1 > %t.simple.txt
+// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-ios7.1-simulator -Xlinker -rpath -Xlinker customrpath -L foo %s 2>&1 > %t.simple.txt
 // RUN: %FileCheck -check-prefix IOS-linker-order %s < %t.simple.txt
 
 // RUN: %swiftc_driver -driver-print-jobs -target armv7-unknown-linux-gnueabihf -Xlinker -rpath -Xlinker customrpath -L foo %s 2>&1 > %t.linux.txt
diff --git a/test/Driver/print_target_info.swift b/test/Driver/print_target_info.swift
index 301473f984747..fdb636dcf1f5d 100644
--- a/test/Driver/print_target_info.swift
+++ b/test/Driver/print_target_info.swift
@@ -7,6 +7,8 @@
 // RUN: %swift_driver -print-target-info -target x86_64-apple-macosx10.15 -target-variant x86_64-apple-ios13-macabi | %FileCheck -check-prefix CHECK-ZIPPERED %s
 // RUN: %target-swift-frontend -print-target-info -target x86_64-apple-macosx10.15 -target-variant x86_64-apple-ios13-macabi | %FileCheck -check-prefix CHECK-ZIPPERED %s
 
+// RUN: %swift_driver -print-target-info -target x86_64-apple-ios12.0 | %FileCheck -check-prefix CHECK-IOS-SIM %s
+
 // CHECK-IOS:   "target": {
 // CHECK-IOS:     "triple": "arm64-apple-ios12.0",
 // CHECK-IOS:     "unversionedTriple": "arm64-apple-ios",
@@ -50,3 +52,11 @@
 // CHECK-ZIPPERED:   "swiftRuntimeCompatibilityVersion": "5.1"
 // CHECK-ZIPPERED:   "librariesRequireRPath": false
 // CHECK-ZIPPERED: }
+
+// CHECK-IOS-SIM:   "target": {
+// CHECK-IOS-SIM:     "triple": "x86_64-apple-ios12.0-simulator",
+// CHECK-IOS-SIM:     "unversionedTriple": "x86_64-apple-ios-simulator",
+// CHECK-IOS-SIM:     "moduleTriple": "x86_64-apple-ios-simulator",
+// CHECK-IOS-SIM:     "swiftRuntimeCompatibilityVersion": "5.0",
+// CHECK-IOS-SIM:     "librariesRequireRPath": true
+// CHECK-IOS-SIM:   }
diff --git a/test/Driver/profiling.swift b/test/Driver/profiling.swift
index f70ec0fe63fae..678e2d4e6abdd 100644
--- a/test/Driver/profiling.swift
+++ b/test/Driver/profiling.swift
@@ -1,20 +1,20 @@
 // RUN: %swiftc_driver -driver-print-jobs -profile-generate -target x86_64-apple-macosx10.9 %s | %FileCheck -check-prefix=CHECK -check-prefix=OSX %s
 
-// RUN: %swiftc_driver -driver-print-jobs -profile-generate -target x86_64-apple-ios7.1 -resource-dir %S/Inputs/fake-resource-dir-old/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=IOS %s
+// RUN: %swiftc_driver -driver-print-jobs -profile-generate -target x86_64-apple-ios7.1-simulator -resource-dir %S/Inputs/fake-resource-dir-old/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=IOS %s
 // RUN: %swiftc_driver -driver-print-jobs -profile-generate -target arm64-apple-ios7.1 -resource-dir %S/Inputs/fake-resource-dir-old/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=IOS %s
 
-// RUN: %swiftc_driver -driver-print-jobs -profile-generate -target x86_64-apple-ios7.1 -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=IOSSIM %s
+// RUN: %swiftc_driver -driver-print-jobs -profile-generate -target x86_64-apple-ios7.1-simulator -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=IOSSIM %s
 // RUN: %swiftc_driver -driver-print-jobs -profile-generate -target arm64-apple-ios7.1 -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=IOS %s
 
-// RUN: %swiftc_driver -driver-print-jobs -profile-generate -target x86_64-apple-tvos9.0 -resource-dir %S/Inputs/fake-resource-dir-old/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=tvOS %s
+// RUN: %swiftc_driver -driver-print-jobs -profile-generate -target x86_64-apple-tvos9.0-simulator -resource-dir %S/Inputs/fake-resource-dir-old/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=tvOS %s
 // RUN: %swiftc_driver -driver-print-jobs -profile-generate -target arm64-apple-tvos9.0 -resource-dir %S/Inputs/fake-resource-dir-old/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=tvOS %s
 
-// RUN: %swiftc_driver -driver-print-jobs -profile-generate -target x86_64-apple-tvos9.0 -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=tvOS_SIM %s
+// RUN: %swiftc_driver -driver-print-jobs -profile-generate -target x86_64-apple-tvos9.0-simulator -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=tvOS_SIM %s
 // RUN: %swiftc_driver -driver-print-jobs -profile-generate -target arm64-apple-tvos9.0 -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=tvOS %s
 
-// RUN: %swiftc_driver -driver-print-jobs -profile-generate -target i386-apple-watchos2.0 -resource-dir %S/Inputs/fake-resource-dir-old/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=watchOS %s
+// RUN: %swiftc_driver -driver-print-jobs -profile-generate -target i386-apple-watchos2.0-simulator -resource-dir %S/Inputs/fake-resource-dir-old/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=watchOS %s
 // RUN: %swiftc_driver -driver-print-jobs -profile-generate -target armv7k-apple-watchos2.0 -resource-dir %S/Inputs/fake-resource-dir-old/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=watchOS %s
-// RUN: %swiftc_driver -driver-print-jobs -profile-generate -target i386-apple-watchos2.0 -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=watchOS_SIM %s
+// RUN: %swiftc_driver -driver-print-jobs -profile-generate -target i386-apple-watchos2.0-simulator -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=watchOS_SIM %s
 // RUN: %swiftc_driver -driver-print-jobs -profile-generate -target armv7k-apple-watchos2.0 -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ %s | %FileCheck -check-prefix=CHECK -check-prefix=watchOS %s
 
 // RUN: %swiftc_driver -driver-print-jobs -profile-generate -target x86_64-unknown-linux-gnu %s | %FileCheck -check-prefix=CHECK -check-prefix=LINUX %s
diff --git a/test/Driver/sanitize_scudo.swift b/test/Driver/sanitize_scudo.swift
index 6f4e66f2612b3..cbc3051be024e 100644
--- a/test/Driver/sanitize_scudo.swift
+++ b/test/Driver/sanitize_scudo.swift
@@ -2,11 +2,11 @@
 // RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=scudo -target arm64-apple-ios7.1 %s 2>&1 | %FileCheck -check-prefix=SCUDO_IOS %s
 // RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=scudo -target arm64-apple-tvos9.0 %s 2>&1 | %FileCheck -check-prefix=SCUDO_tvOS %s
 // RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=scudo -target armv7k-apple-watchos2.0 %s 2>&1 | %FileCheck -check-prefix=SCUDO_watchOS %s
-// RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=scudo -target i386-apple-watchos2.0 %s 2>&1 | %FileCheck -check-prefix=SCUDO_watchOS_SIM %s
+// RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=scudo -target i386-apple-watchos2.0-simulator %s 2>&1 | %FileCheck -check-prefix=SCUDO_watchOS_SIM %s
 // RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=scudo -target i386-apple-macosx10.9 %s 2>&1 | %FileCheck -check-prefix=SCUDO_OSX_32 %s
-// RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=scudo -target x86_64-apple-ios7.1 %s 2>&1 | %FileCheck -check-prefix=SCUDO_IOSSIM %s
+// RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=scudo -target x86_64-apple-ios7.1-simulator %s 2>&1 | %FileCheck -check-prefix=SCUDO_IOSSIM %s
 // RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=scudo -target x86_64-apple-macosx10.9 %s 2>&1 | %FileCheck -check-prefix=SCUDO_OSX_64 %s
-// RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=scudo -target x86_64-apple-tvos9.0 %s 2>&1 | %FileCheck -check-prefix=SCUDO_tvOS_SIM %s
+// RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=scudo -target x86_64-apple-tvos9.0-simulator %s 2>&1 | %FileCheck -check-prefix=SCUDO_tvOS_SIM %s
 // RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=scudo -target x86_64-unknown-windows-msvc %s 2>&1 | %FileCheck -check-prefix=SCUDO_WINDOWS %s
 
 // RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=scudo,address -target x86_64-unknown-linux-gnu %s 2>&1 | %FileCheck -check-prefix=SCUDO_ASAN %s
@@ -24,11 +24,11 @@
 // SCUDO_LINUX-SAME: -fsanitize=scudo
 // SCUDO_OSX_32: unsupported option '-sanitize=scudo' for target 'i386-apple-macosx10.9'
 // SCUDO_OSX_64: unsupported option '-sanitize=scudo' for target 'x86_64-apple-macosx10.9'
-// SCUDO_IOSSIM: unsupported option '-sanitize=scudo' for target 'x86_64-apple-ios7.1'
+// SCUDO_IOSSIM: unsupported option '-sanitize=scudo' for target 'x86_64-apple-ios7.1-simulator'
 // SCUDO_IOS: unsupported option '-sanitize=scudo' for target 'arm64-apple-ios7.1'
-// SCUDO_tvOS_SIM: unsupported option '-sanitize=scudo' for target 'x86_64-apple-tvos9.0'
+// SCUDO_tvOS_SIM: unsupported option '-sanitize=scudo' for target 'x86_64-apple-tvos9.0-simulator'
 // SCUDO_tvOS: unsupported option '-sanitize=scudo' for target 'arm64-apple-tvos9.0'
-// SCUDO_watchOS_SIM: unsupported option '-sanitize=scudo' for target 'i386-apple-watchos2.0'
+// SCUDO_watchOS_SIM: unsupported option '-sanitize=scudo' for target 'i386-apple-watchos2.0-simulator'
 // SCUDO_watchOS: unsupported option '-sanitize=scudo' for target 'armv7k-apple-watchos2.0'
 // SCUDO_WINDOWS: unsupported option '-sanitize=scudo' for target 'x86_64-unknown-windows-msvc'
 
diff --git a/test/Driver/sanitizers.swift b/test/Driver/sanitizers.swift
index 54935b7f7772e..d4dc5cea6de30 100644
--- a/test/Driver/sanitizers.swift
+++ b/test/Driver/sanitizers.swift
@@ -3,11 +3,11 @@
  */
 // RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=address -target x86_64-apple-macosx10.9 %s | %FileCheck -check-prefix=ASAN -check-prefix=ASAN_OSX %s
 // RUN: not %swiftc_driver -driver-print-jobs -sanitize=fuzzer -target x86_64-apple-macosx10.9 -resource-dir %S/Inputs/nonexistent-resource-dir %s 2>&1 | %FileCheck -check-prefix=FUZZER_NONEXISTENT %s
-// RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=address -target x86_64-apple-ios7.1 %s | %FileCheck -check-prefix=ASAN -check-prefix=ASAN_IOSSIM %s
+// RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=address -target x86_64-apple-ios7.1-simulator %s | %FileCheck -check-prefix=ASAN -check-prefix=ASAN_IOSSIM %s
 // RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=address -target arm64-apple-ios7.1 %s  | %FileCheck -check-prefix=ASAN -check-prefix=ASAN_IOS %s
-// RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=address -target x86_64-apple-tvos9.0 %s | %FileCheck -check-prefix=ASAN -check-prefix=ASAN_tvOS_SIM %s
+// RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=address -target x86_64-apple-tvos9.0-simulator %s | %FileCheck -check-prefix=ASAN -check-prefix=ASAN_tvOS_SIM %s
 // RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=address -target arm64-apple-tvos9.0 %s  | %FileCheck -check-prefix=ASAN -check-prefix=ASAN_tvOS %s
-// RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=address -target i386-apple-watchos2.0 %s   | %FileCheck -check-prefix=ASAN -check-prefix=ASAN_watchOS_SIM %s
+// RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=address -target i386-apple-watchos2.0-simulator %s   | %FileCheck -check-prefix=ASAN -check-prefix=ASAN_watchOS_SIM %s
 // RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=address -target armv7k-apple-watchos2.0 %s | %FileCheck -check-prefix=ASAN -check-prefix=ASAN_watchOS %s
 // RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=address -target x86_64-unknown-linux-gnu %s 2>&1 | %FileCheck -check-prefix=ASAN_LINUX %s
 // RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=address -target x86_64-unknown-windows-msvc %s 2>&1 | %FileCheck -check-prefix=ASAN_WINDOWS %s
@@ -17,11 +17,11 @@
  */
 // RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=thread -target x86_64-apple-macosx10.9 %s | %FileCheck -check-prefix=TSAN -check-prefix=TSAN_OSX %s
 // RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=thread -target x86-apple-macosx10.9 %s 2>&1 | %FileCheck -check-prefix=TSAN_OSX_32 %s
-// RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=thread -target x86_64-apple-ios7.1 %s 2>&1 | %FileCheck -check-prefix=TSAN_IOSSIM %s
+// RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=thread -target x86_64-apple-ios7.1-simulator %s 2>&1 | %FileCheck -check-prefix=TSAN_IOSSIM %s
 // RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=thread -target arm64-apple-ios7.1 %s 2>&1 | %FileCheck -check-prefix=TSAN_IOS %s
-// RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=thread -target x86_64-apple-tvos9.0 %s 2>&1 | %FileCheck -check-prefix=TSAN_tvOS_SIM %s
+// RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=thread -target x86_64-apple-tvos9.0-simulator %s 2>&1 | %FileCheck -check-prefix=TSAN_tvOS_SIM %s
 // RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=thread -target arm64-apple-tvos9.0 %s 2>&1 | %FileCheck -check-prefix=TSAN_tvOS %s
-// RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=thread -target i386-apple-watchos2.0 %s 2>&1 | %FileCheck -check-prefix=TSAN_watchOS_SIM %s
+// RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=thread -target i386-apple-watchos2.0-simulator %s 2>&1 | %FileCheck -check-prefix=TSAN_watchOS_SIM %s
 // RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=thread -target armv7k-apple-watchos2.0 %s 2>&1  | %FileCheck -check-prefix=TSAN_watchOS %s
 // RUN: not %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=thread -target x86_64-unknown-windows-msvc %s 2>&1 | %FileCheck -check-prefix=TSAN_WINDOWS %s
 // RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=thread -target x86_64-unknown-linux-gnu %s 2>&1 | %FileCheck -check-prefix=TSAN_LINUX %s
@@ -30,11 +30,11 @@
  * Undefined Behavior Sanitizer Tests  (ubsan)
  */
 // RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=undefined -target x86_64-apple-macosx10.9 %s | %FileCheck -check-prefix=UBSAN -check-prefix=UBSAN_OSX %s
-// RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=undefined -target x86_64-apple-ios7.1 %s | %FileCheck -check-prefix=UBSAN -check-prefix=UBSAN_IOSSIM %s
+// RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=undefined -target x86_64-apple-ios7.1-simulator %s | %FileCheck -check-prefix=UBSAN -check-prefix=UBSAN_IOSSIM %s
 // RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=undefined -target arm64-apple-ios7.1 %s  | %FileCheck -check-prefix=UBSAN -check-prefix=UBSAN_IOS %s
-// RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=undefined -target x86_64-apple-tvos9.0 %s | %FileCheck -check-prefix=UBSAN -check-prefix=UBSAN_tvOS_SIM %s
+// RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=undefined -target x86_64-apple-tvos9.0-simulator %s | %FileCheck -check-prefix=UBSAN -check-prefix=UBSAN_tvOS_SIM %s
 // RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=undefined -target arm64-apple-tvos9.0 %s  | %FileCheck -check-prefix=UBSAN -check-prefix=UBSAN_tvOS %s
-// RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=undefined -target i386-apple-watchos2.0 %s   | %FileCheck -check-prefix=UBSAN -check-prefix=UBSAN_watchOS_SIM %s
+// RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=undefined -target i386-apple-watchos2.0-simulator %s   | %FileCheck -check-prefix=UBSAN -check-prefix=UBSAN_watchOS_SIM %s
 // RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=undefined -target armv7k-apple-watchos2.0 %s | %FileCheck -check-prefix=UBSAN -check-prefix=UBSAN_watchOS %s
 // RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=undefined -target x86_64-unknown-linux-gnu %s 2>&1 | %FileCheck -check-prefix=UBSAN_LINUX %s
 // RUN: %swiftc_driver -resource-dir %S/Inputs/fake-resource-dir/lib/swift/ -driver-print-jobs -sanitize=undefined -target x86_64-unknown-windows-msvc %s 2>&1 | %FileCheck -check-prefix=UBSAN_WINDOWS %s
@@ -79,11 +79,11 @@
 
 // TSAN_OSX: lib{{/|\\\\}}swift{{/|\\\\}}clang{{/|\\\\}}lib{{/|\\\\}}darwin{{/|\\\\}}libclang_rt.tsan_osx_dynamic.dylib
 // TSAN_OSX_32: unsupported option '-sanitize=thread' for target 'x86-apple-macosx10.9'
-// TSAN_IOSSIM: unsupported option '-sanitize=thread' for target 'x86_64-apple-ios7.1'
+// TSAN_IOSSIM: unsupported option '-sanitize=thread' for target 'x86_64-apple-ios7.1-simulator'
 // TSAN_IOS: unsupported option '-sanitize=thread' for target 'arm64-apple-ios7.1'
-// TSAN_tvOS_SIM: unsupported option '-sanitize=thread' for target 'x86_64-apple-tvos9.0'
+// TSAN_tvOS_SIM: unsupported option '-sanitize=thread' for target 'x86_64-apple-tvos9.0-simulator'
 // TSAN_tvOS: unsupported option '-sanitize=thread' for target 'arm64-apple-tvos9.0'
-// TSAN_watchOS_SIM: unsupported option '-sanitize=thread' for target 'i386-apple-watchos2.0'
+// TSAN_watchOS_SIM: unsupported option '-sanitize=thread' for target 'i386-apple-watchos2.0-simulator'
 // TSAN_watchOS: unsupported option '-sanitize=thread' for target 'armv7k-apple-watchos2.0'
 // FUZZER_NONEXISTENT: unsupported option '-sanitize=fuzzer' for target 'x86_64-apple-macosx10.9'
 // TSAN_LINUX: -fsanitize=thread -lBlocksRuntime -ldispatch
diff --git a/test/Parse/ConditionalCompilation/simulatorTargetEnv.swift b/test/Parse/ConditionalCompilation/simulatorTargetEnv.swift
index 63e54ed24f7f9..232bc41fdd0b4 100644
--- a/test/Parse/ConditionalCompilation/simulatorTargetEnv.swift
+++ b/test/Parse/ConditionalCompilation/simulatorTargetEnv.swift
@@ -1,6 +1,6 @@
-// RUN: %swift -swift-version 4 -typecheck %s -verify -target x86_64-apple-ios7.0 -parse-stdlib
+// RUN: %swift -swift-version 4 -typecheck %s -verify -target x86_64-apple-ios7.0-simulator -parse-stdlib
 // RUN: %swift -swift-version 4 -typecheck %s -verify -target x86_64-unknown-linux-simulator -parse-stdlib
-// RUN: %swift-ide-test -swift-version 4 -test-input-complete -source-filename=%s -target x86_64-apple-ios7.0
+// RUN: %swift-ide-test -swift-version 4 -test-input-complete -source-filename=%s -target x86_64-apple-ios7.0-simulator
 
 #if !targetEnvironment(simulator)
 // This block should not parse.
diff --git a/test/Serialization/load-target-normalization.swift b/test/Serialization/load-target-normalization.swift
index 21040c0c2aab8..e1120d75ac3ff 100644
--- a/test/Serialization/load-target-normalization.swift
+++ b/test/Serialization/load-target-normalization.swift
@@ -109,15 +109,6 @@ import ForeignModule
 // RUN: not %target-swift-frontend %s -typecheck -I %t -parse-stdlib -Xcc -arch -Xcc i386 -target i386-apple-tvos40-simulator 2>&1 | %FileCheck -DNORM=i386-apple-tvos-simulator %s
 // RUN: not %target-swift-frontend %s -typecheck -I %t -parse-stdlib -Xcc -arch -Xcc i386 -target i386-apple-watchos9.1.1-simulator 2>&1 | %FileCheck -DNORM=i386-apple-watchos-simulator %s
 
-// simulator should be inferred when an Intel architecture is used with iOS, tvOS, or watchOS.
-
-// RUN: not %target-swift-frontend %s -typecheck -I %t -parse-stdlib -Xcc -arch -Xcc i386 -target x86_64-apple-ios40.0 2>&1 | %FileCheck -DNORM=x86_64-apple-ios-simulator %s
-// RUN: not %target-swift-frontend %s -typecheck -I %t -parse-stdlib -Xcc -arch -Xcc i386 -target x86_64-apple-tvos40 2>&1 | %FileCheck -DNORM=x86_64-apple-tvos-simulator %s
-// RUN: not %target-swift-frontend %s -typecheck -I %t -parse-stdlib -Xcc -arch -Xcc i386 -target x86_64-apple-watchos9.1.1 2>&1 | %FileCheck -DNORM=x86_64-apple-watchos-simulator %s
-// RUN: not %target-swift-frontend %s -typecheck -I %t -parse-stdlib -Xcc -arch -Xcc i386 -target i386-apple-ios40.0 2>&1 | %FileCheck -DNORM=i386-apple-ios-simulator %s
-// RUN: not %target-swift-frontend %s -typecheck -I %t -parse-stdlib -Xcc -arch -Xcc i386 -target i386-apple-tvos40 2>&1 | %FileCheck -DNORM=i386-apple-tvos-simulator %s
-// RUN: not %target-swift-frontend %s -typecheck -I %t -parse-stdlib -Xcc -arch -Xcc i386 -target i386-apple-watchos9.1.1 2>&1 | %FileCheck -DNORM=i386-apple-watchos-simulator %s
-
 // Other environments should be passed through.
 
 // RUN: not %target-swift-frontend %s -typecheck -I %t -parse-stdlib -Xcc -arch -Xcc i386 -target i386-apple-ios40.0-in_spaaaaaaace 2>&1 | %FileCheck -DNORM=i386-apple-ios-in_spaaaaaaace %s