Index: lib/Basic/Targets.h
===================================================================
--- lib/Basic/Targets.h
+++ lib/Basic/Targets.h
@@ -40,7 +40,7 @@
                      bool Tuning = true);
 
 LLVM_LIBRARY_VISIBILITY
-void addMinGWDefines(const clang::LangOptions &Opts,
+void addMinGWDefines(const llvm::Triple &Triple, const clang::LangOptions &Opts,
                      clang::MacroBuilder &Builder);
 
 LLVM_LIBRARY_VISIBILITY
Index: lib/Basic/Targets.cpp
===================================================================
--- lib/Basic/Targets.cpp
+++ lib/Basic/Targets.cpp
@@ -97,7 +97,14 @@
   }
 }
 
-void addMinGWDefines(const LangOptions &Opts, MacroBuilder &Builder) {
+void addMinGWDefines(const llvm::Triple &Triple, const LangOptions &Opts,
+                     MacroBuilder &Builder) {
+  DefineStd(Builder, "WIN32", Opts);
+  DefineStd(Builder, "WINNT", Opts);
+  if (Triple.isArch64Bit()) {
+    DefineStd(Builder, "WIN64", Opts);
+    Builder.defineMacro("__MINGW64__");
+  }
   Builder.defineMacro("__MSVCRT__");
   Builder.defineMacro("__MINGW32__");
   addCygMingDefines(Opts, Builder);
Index: lib/Basic/Targets/AArch64.h
===================================================================
--- lib/Basic/Targets/AArch64.h
+++ lib/Basic/Targets/AArch64.h
@@ -122,9 +122,6 @@
     : public WindowsARM64TargetInfo {
 public:
   MinGWARM64TargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts);
-
-  void getTargetDefines(const LangOptions &Opts,
-                        MacroBuilder &Builder) const override;
 };
 
 class LLVM_LIBRARY_VISIBILITY AArch64beTargetInfo : public AArch64TargetInfo {
Index: lib/Basic/Targets/AArch64.cpp
===================================================================
--- lib/Basic/Targets/AArch64.cpp
+++ lib/Basic/Targets/AArch64.cpp
@@ -474,8 +474,6 @@
 void MicrosoftARM64TargetInfo::getVisualStudioDefines(
     const LangOptions &Opts, MacroBuilder &Builder) const {
   WindowsTargetInfo<AArch64leTargetInfo>::getVisualStudioDefines(Opts, Builder);
-  Builder.defineMacro("_WIN32", "1");
-  Builder.defineMacro("_WIN64", "1");
   Builder.defineMacro("_M_ARM64", "1");
 }
 
@@ -491,17 +489,6 @@
   TheCXXABI.set(TargetCXXABI::GenericAArch64);
 }
 
-void MinGWARM64TargetInfo::getTargetDefines(const LangOptions &Opts,
-                                            MacroBuilder &Builder) const {
-  WindowsTargetInfo::getTargetDefines(Opts, Builder);
-  Builder.defineMacro("_WIN32", "1");
-  Builder.defineMacro("_WIN64", "1");
-  Builder.defineMacro("WIN32", "1");
-  Builder.defineMacro("WIN64", "1");
-  addMinGWDefines(Opts, Builder);
-}
-
-
 DarwinAArch64TargetInfo::DarwinAArch64TargetInfo(const llvm::Triple &Triple,
                                                  const TargetOptions &Opts)
     : DarwinTargetInfo<AArch64leTargetInfo>(Triple, Opts) {
Index: lib/Basic/Targets/ARM.cpp
===================================================================
--- lib/Basic/Targets/ARM.cpp
+++ lib/Basic/Targets/ARM.cpp
@@ -999,11 +999,8 @@
 void MinGWARMTargetInfo::getTargetDefines(const LangOptions &Opts,
                                           MacroBuilder &Builder) const {
   WindowsARMTargetInfo::getTargetDefines(Opts, Builder);
-  DefineStd(Builder, "WIN32", Opts);
-  DefineStd(Builder, "WINNT", Opts);
   Builder.defineMacro("_ARM_");
   Builder.defineMacro("__ARM_DWARF_EH__");
-  addMinGWDefines(Opts, Builder);
 }
 
 CygwinARMTargetInfo::CygwinARMTargetInfo(const llvm::Triple &Triple,
Index: lib/Basic/Targets/OSTargets.h
===================================================================
--- lib/Basic/Targets/OSTargets.h
+++ lib/Basic/Targets/OSTargets.h
@@ -572,6 +572,11 @@
   void getOSDefines(const LangOptions &Opts, const llvm::Triple &Triple,
                     MacroBuilder &Builder) const override {
     Builder.defineMacro("_WIN32");
+    if (Triple.isArch64Bit())
+      Builder.defineMacro("_WIN64");
+    if (Triple.isWindowsGNUEnvironment())
+      addMinGWDefines(Triple, Opts, Builder);
+
   }
   void getVisualStudioDefines(const LangOptions &Opts,
                               MacroBuilder &Builder) const {
Index: lib/Basic/Targets/X86.h
===================================================================
--- lib/Basic/Targets/X86.h
+++ lib/Basic/Targets/X86.h
@@ -410,11 +410,6 @@
                         ? "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
                         : "e-m:e-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32");
   }
-
-  void getTargetDefines(const LangOptions &Opts,
-                        MacroBuilder &Builder) const override {
-    WindowsTargetInfo<X86_32TargetInfo>::getTargetDefines(Opts, Builder);
-  }
 };
 
 // x86-32 Windows Visual Studio target
@@ -451,10 +446,7 @@
   void getTargetDefines(const LangOptions &Opts,
                         MacroBuilder &Builder) const override {
     WindowsX86_32TargetInfo::getTargetDefines(Opts, Builder);
-    DefineStd(Builder, "WIN32", Opts);
-    DefineStd(Builder, "WINNT", Opts);
     Builder.defineMacro("_X86_");
-    addMinGWDefines(Opts, Builder);
   }
 };
 
@@ -658,12 +650,6 @@
     IntPtrType = SignedLongLong;
   }
 
-  void getTargetDefines(const LangOptions &Opts,
-                        MacroBuilder &Builder) const override {
-    WindowsTargetInfo<X86_64TargetInfo>::getTargetDefines(Opts, Builder);
-    Builder.defineMacro("_WIN64");
-  }
-
   BuiltinVaListKind getBuiltinVaListKind() const override {
     return TargetInfo::CharPtrBuiltinVaList;
   }
@@ -726,9 +712,6 @@
   void getTargetDefines(const LangOptions &Opts,
                         MacroBuilder &Builder) const override {
     WindowsX86_64TargetInfo::getTargetDefines(Opts, Builder);
-    DefineStd(Builder, "WIN64", Opts);
-    Builder.defineMacro("__MINGW64__");
-    addMinGWDefines(Opts, Builder);
 
     // GCC defines this macro when it is using __gxx_personality_seh0.
     if (!Opts.SjLjExceptions)
Index: test/Preprocessor/predefined-macros.c
===================================================================
--- test/Preprocessor/predefined-macros.c
+++ test/Preprocessor/predefined-macros.c
@@ -193,12 +193,71 @@
 // MSCOPE:#define __OPENCL_MEMORY_SCOPE_WORK_GROUP 1
 // MSCOPE:#define __OPENCL_MEMORY_SCOPE_WORK_ITEM 0
 
+// RUN: %clang_cc1 -triple i386-windows %s -E -dM -o - \
+// RUN:   | FileCheck -match-full-lines %s --check-prefix=CHECK-X86-WIN
+
+// CHECK-X86-WIN: #define _WIN32 1
+// CHECK-X86-WIN-NOT: #define _WIN64 1
+// CHECK-X86-WIN-NOT: #define WINNT 1
+// CHECK-X86-WIN-NOT: #define WIN32 1
+// CHECK-X86-WIN-NOT: #define WIN64 1
+
+
+// RUN: %clang_cc1 -triple thumbv7-windows %s -E -dM -o - \
+// RUN:   | FileCheck -match-full-lines %s --check-prefix=CHECK-ARM-WIN
+
+// CHECK-ARM-WIN: #define _WIN32 1
+// CHECK-ARM-WIN-NOT: #define _WIN64 1
+// CHECK-ARM-WIN-NOT: #define WINNT 1
+// CHECK-ARM-WIN-NOT: #define WIN32 1
+// CHECK-ARM-WIN-NOT: #define WIN64 1
+
+
+// RUN: %clang_cc1 -triple x86_64-windows %s -E -dM -o - \
+// RUN:   | FileCheck -match-full-lines %s --check-prefix=CHECK-AMD64-WIN
+
+// CHECK-AMD64-WIN: #define _WIN32 1
+// CHECK-AMD64-WIN: #define _WIN64 1
+// CHECK-AMD64-WIN-NOT: #define WINNT 1
+// CHECK-AMD64-WIN-NOT: #define WIN32 1
+// CHECK-AMD64-WIN-NOT: #define WIN64 1
+
 // RUN: %clang_cc1 -triple aarch64-windows %s -E -dM -o - \
 // RUN:   | FileCheck -match-full-lines %s --check-prefix=CHECK-ARM64-WIN
 
 // CHECK-ARM64-WIN: #define _M_ARM64 1
 // CHECK-ARM64-WIN: #define _WIN32 1
 // CHECK-ARM64-WIN: #define _WIN64 1
+// CHECK-ARM64-WIN-NOT: #define WINNT 1
+// CHECK-ARM64-WIN-NOT: #define WIN32 1
+// CHECK-ARM64-WIN-NOT: #define WIN64 1
+
+// RUN: %clang_cc1 -triple i686-windows-gnu %s -E -dM -o - \
+// RUN:   | FileCheck -match-full-lines %s --check-prefix=CHECK-X86-MINGW
+
+// CHECK-X86-MINGW: #define WIN32 1
+// CHECK-X86-MINGW: #define WINNT 1
+// CHECK-X86-MINGW: #define _WIN32 1
+// CHECK-X86-MINGW-NOT: #define WIN64 1
+// CHECK-X86-MINGW-NOT: #define _WIN64 1
+
+// RUN: %clang_cc1 -triple thumbv7-windows-gnu %s -E -dM -o - \
+// RUN:   | FileCheck -match-full-lines %s --check-prefix=CHECK-ARM-MINGW
+
+// CHECK-ARM-MINGW: #define WIN32 1
+// CHECK-ARM-MINGW: #define WINNT 1
+// CHECK-ARM-MINGW: #define _WIN32 1
+// CHECK-ARM-MINGW-NOT: #define WIN64 1
+// CHECK-ARM-MINGW-NOT: #define _WIN64 1
+
+// RUN: %clang_cc1 -triple x86_64-windows-gnu %s -E -dM -o - \
+// RUN:   | FileCheck -match-full-lines %s --check-prefix=CHECK-AMD64-MINGW
+
+// CHECK-AMD64-MINGW: #define WIN32 1
+// CHECK-AMD64-MINGW: #define WIN64 1
+// CHECK-AMD64-MINGW: #define WINNT 1
+// CHECK-AMD64-MINGW: #define _WIN32 1
+// CHECK-AMD64-MINGW: #define _WIN64 1
 
 // RUN: %clang_cc1 -triple aarch64-windows-gnu %s -E -dM -o - \
 // RUN:   | FileCheck -match-full-lines %s --check-prefix=CHECK-ARM64-MINGW
@@ -206,6 +265,7 @@
 // CHECK-ARM64-MINGW-NOT: #define _M_ARM64 1
 // CHECK-ARM64-MINGW: #define WIN32 1
 // CHECK-ARM64-MINGW: #define WIN64 1
+// CHECK-ARM64-MINGW: #define WINNT 1
 // CHECK-ARM64-MINGW: #define _WIN32 1
 // CHECK-ARM64-MINGW: #define _WIN64 1
 // CHECK-ARM64-MINGW: #define __aarch64__ 1