Index: cfe/trunk/lib/Basic/Targets/X86.h
===================================================================
--- cfe/trunk/lib/Basic/Targets/X86.h
+++ cfe/trunk/lib/Basic/Targets/X86.h
@@ -81,6 +81,7 @@
   bool HasMPX = false;
   bool HasSHSTK = false;
   bool HasSGX = false;
+  bool HasCX8 = false;
   bool HasCX16 = false;
   bool HasFXSR = false;
   bool HasXSAVE = false;
@@ -344,9 +345,8 @@
          (1 << TargetInfo::LongDouble));
 
     // x86-32 has atomics up to 8 bytes
-    // FIXME: Check that we actually have cmpxchg8b before setting
-    // MaxAtomicInlineWidth. (cmpxchg8b is an i586 instruction.)
-    MaxAtomicPromoteWidth = MaxAtomicInlineWidth = 64;
+    MaxAtomicPromoteWidth = 64;
+    MaxAtomicInlineWidth = 32;
   }
 
   BuiltinVaListKind getBuiltinVaListKind() const override {
@@ -382,6 +382,11 @@
     return X86TargetInfo::validateOperandSize(Constraint, Size);
   }
 
+  void setMaxAtomicWidth() override {
+    if (hasFeature("cx8"))
+      MaxAtomicInlineWidth = 64;
+  }
+
   ArrayRef<Builtin::Info> getTargetBuiltins() const override;
 };
 
Index: cfe/trunk/lib/Basic/Targets/X86.cpp
===================================================================
--- cfe/trunk/lib/Basic/Targets/X86.cpp
+++ cfe/trunk/lib/Basic/Targets/X86.cpp
@@ -115,6 +115,11 @@
   if (Kind != CK_Lakemont)
     setFeatureEnabledImpl(Features, "x87", true);
 
+  // Enable cmpxchg8 for i586 and greater CPUs. Include generic for backwards
+  // compatibility.
+  if (Kind >= CK_i586 || Kind == CK_Generic)
+    setFeatureEnabledImpl(Features, "cx8", true);
+
   switch (Kind) {
   case CK_Generic:
   case CK_i386:
@@ -777,6 +782,8 @@
       HasMOVBE = true;
     } else if (Feature == "+sgx") {
       HasSGX = true;
+    } else if (Feature == "+cx8") {
+      HasCX8 = true;
     } else if (Feature == "+cx16") {
       HasCX16 = true;
     } else if (Feature == "+fxsr") {
@@ -1275,12 +1282,12 @@
     break;
   }
 
-  if (CPU >= CK_i486) {
+  if (CPU >= CK_i486 || CPU == CK_Generic) {
     Builder.defineMacro("__GCC_HAVE_SYNC_COMPARE_AND_SWAP_1");
     Builder.defineMacro("__GCC_HAVE_SYNC_COMPARE_AND_SWAP_2");
     Builder.defineMacro("__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4");
   }
-  if (CPU >= CK_i586)
+  if (HasCX8)
     Builder.defineMacro("__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8");
   if (HasCX16 && getTriple().getArch() == llvm::Triple::x86_64)
     Builder.defineMacro("__GCC_HAVE_SYNC_COMPARE_AND_SWAP_16");
@@ -1394,6 +1401,7 @@
       .Case("clflushopt", HasCLFLUSHOPT)
       .Case("clwb", HasCLWB)
       .Case("clzero", HasCLZERO)
+      .Case("cx8", HasCX8)
       .Case("cx16", HasCX16)
       .Case("f16c", HasF16C)
       .Case("fma", HasFMA)
Index: cfe/trunk/test/CodeGen/attr-cpuspecific.c
===================================================================
--- cfe/trunk/test/CodeGen/attr-cpuspecific.c
+++ cfe/trunk/test/CodeGen/attr-cpuspecific.c
@@ -254,6 +254,6 @@
 // WINDOWS: define dso_local i32 @DispatchFirst.B
 // WINDOWS: ret i32 1
 
-// CHECK: attributes #[[S]] = {{.*}}"target-features"="+avx,+cmov,+f16c,+mmx,+popcnt,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave"
-// CHECK: attributes #[[K]] = {{.*}}"target-features"="+adx,+avx,+avx2,+avx512cd,+avx512er,+avx512f,+avx512pf,+bmi,+cmov,+f16c,+fma,+lzcnt,+mmx,+movbe,+popcnt,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave"
-// CHECK: attributes #[[O]] = {{.*}}"target-features"="+cmov,+mmx,+movbe,+sse,+sse2,+sse3,+ssse3,+x87"
+// CHECK: attributes #[[S]] = {{.*}}"target-features"="+avx,+cmov,+cx8,+f16c,+mmx,+popcnt,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave"
+// CHECK: attributes #[[K]] = {{.*}}"target-features"="+adx,+avx,+avx2,+avx512cd,+avx512er,+avx512f,+avx512pf,+bmi,+cmov,+cx8,+f16c,+fma,+lzcnt,+mmx,+movbe,+popcnt,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave"
+// CHECK: attributes #[[O]] = {{.*}}"target-features"="+cmov,+cx8,+mmx,+movbe,+sse,+sse2,+sse3,+ssse3,+x87"
Index: cfe/trunk/test/CodeGen/attr-target-x86-mmx.c
===================================================================
--- cfe/trunk/test/CodeGen/attr-target-x86-mmx.c
+++ cfe/trunk/test/CodeGen/attr-target-x86-mmx.c
@@ -19,4 +19,4 @@
   _mm_srai_pi32(a, c);
 }
 
-// CHECK: "target-features"="+mmx,+sse,+x87"
+// CHECK: "target-features"="+cx8,+mmx,+sse,+x87"
Index: cfe/trunk/test/CodeGen/attr-target-x86.c
===================================================================
--- cfe/trunk/test/CodeGen/attr-target-x86.c
+++ cfe/trunk/test/CodeGen/attr-target-x86.c
@@ -48,11 +48,11 @@
 // CHECK: qq{{.*}} #6
 // CHECK: lake{{.*}} #7
 // CHECK: use_before_def{{.*}} #7
-// CHECK: #0 = {{.*}}"target-cpu"="i686" "target-features"="+x87"
-// CHECK: #1 = {{.*}}"target-cpu"="ivybridge" "target-features"="+avx,+cx16,+f16c,+fsgsbase,+fxsr,+mmx,+pclmul,+popcnt,+rdrnd,+sahf,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave,+xsaveopt"
-// CHECK: #2 = {{.*}}"target-cpu"="i686" "target-features"="+x87,-aes,-avx,-avx2,-avx512bitalg,-avx512bw,-avx512cd,-avx512dq,-avx512er,-avx512f,-avx512ifma,-avx512pf,-avx512vbmi,-avx512vbmi2,-avx512vl,-avx512vnni,-avx512vpopcntdq,-f16c,-fma,-fma4,-gfni,-pclmul,-sha,-sse2,-sse3,-sse4.1,-sse4.2,-sse4a,-ssse3,-vaes,-vpclmulqdq,-xop,-xsave,-xsaveopt"
-// CHECK: #3 = {{.*}}"target-cpu"="i686" "target-features"="+mmx,+popcnt,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87"
-// CHECK: #4 = {{.*}}"target-cpu"="i686" "target-features"="+x87,-avx,-avx2,-avx512bitalg,-avx512bw,-avx512cd,-avx512dq,-avx512er,-avx512f,-avx512ifma,-avx512pf,-avx512vbmi,-avx512vbmi2,-avx512vl,-avx512vnni,-avx512vpopcntdq,-f16c,-fma,-fma4,-sse4.1,-sse4.2,-vaes,-vpclmulqdq,-xop,-xsave,-xsaveopt"
-// CHECK: #5 = {{.*}}"target-cpu"="ivybridge" "target-features"="+avx,+cx16,+f16c,+fsgsbase,+fxsr,+mmx,+pclmul,+popcnt,+rdrnd,+sahf,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave,+xsaveopt,-aes,-vaes"
-// CHECK: #6 = {{.*}}"target-cpu"="i686" "target-features"="+x87,-3dnow,-3dnowa,-mmx"
-// CHECK: #7 = {{.*}}"target-cpu"="lakemont" "target-features"="+mmx"
+// CHECK: #0 = {{.*}}"target-cpu"="i686" "target-features"="+cx8,+x87"
+// CHECK: #1 = {{.*}}"target-cpu"="ivybridge" "target-features"="+avx,+cx16,+cx8,+f16c,+fsgsbase,+fxsr,+mmx,+pclmul,+popcnt,+rdrnd,+sahf,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave,+xsaveopt"
+// CHECK: #2 = {{.*}}"target-cpu"="i686" "target-features"="+cx8,+x87,-aes,-avx,-avx2,-avx512bitalg,-avx512bw,-avx512cd,-avx512dq,-avx512er,-avx512f,-avx512ifma,-avx512pf,-avx512vbmi,-avx512vbmi2,-avx512vl,-avx512vnni,-avx512vpopcntdq,-f16c,-fma,-fma4,-gfni,-pclmul,-sha,-sse2,-sse3,-sse4.1,-sse4.2,-sse4a,-ssse3,-vaes,-vpclmulqdq,-xop,-xsave,-xsaveopt"
+// CHECK: #3 = {{.*}}"target-cpu"="i686" "target-features"="+cx8,+mmx,+popcnt,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87"
+// CHECK: #4 = {{.*}}"target-cpu"="i686" "target-features"="+cx8,+x87,-avx,-avx2,-avx512bitalg,-avx512bw,-avx512cd,-avx512dq,-avx512er,-avx512f,-avx512ifma,-avx512pf,-avx512vbmi,-avx512vbmi2,-avx512vl,-avx512vnni,-avx512vpopcntdq,-f16c,-fma,-fma4,-sse4.1,-sse4.2,-vaes,-vpclmulqdq,-xop,-xsave,-xsaveopt"
+// CHECK: #5 = {{.*}}"target-cpu"="ivybridge" "target-features"="+avx,+cx16,+cx8,+f16c,+fsgsbase,+fxsr,+mmx,+pclmul,+popcnt,+rdrnd,+sahf,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave,+xsaveopt,-aes,-vaes"
+// CHECK: #6 = {{.*}}"target-cpu"="i686" "target-features"="+cx8,+x87,-3dnow,-3dnowa,-mmx"
+// CHECK: #7 = {{.*}}"target-cpu"="lakemont" "target-features"="+cx8,+mmx"
Index: cfe/trunk/test/CodeGen/attr-target-x87-softfp.c
===================================================================
--- cfe/trunk/test/CodeGen/attr-target-x87-softfp.c
+++ cfe/trunk/test/CodeGen/attr-target-x87-softfp.c
@@ -7,10 +7,10 @@
 // CHECK: foo{{.*}} #0
 // CHECK: bar{{.*}} #1
 
-// CHECK: #0 = {{.*}}"target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87"
+// CHECK: #0 = {{.*}}"target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87"
 // HARD: "use-soft-float"="false"
 // SOFT: "use-soft-float"="true"
 
-// CHECK: #1 = {{.*}}"target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,-x87"
+// CHECK: #1 = {{.*}}"target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,-x87"
 // HARD: "use-soft-float"="false"
 // SOFT: "use-soft-float"="true"
Index: cfe/trunk/test/Preprocessor/init.c
===================================================================
--- cfe/trunk/test/Preprocessor/init.c
+++ cfe/trunk/test/Preprocessor/init.c
@@ -2845,8 +2845,9 @@
 // I386:#define __i386__ 1
 // I386:#define i386 1
 //
-// RUN: %clang_cc1 -E -dM -ffreestanding -triple=i386-pc-linux-gnu -target-cpu pentium4 < /dev/null | FileCheck -match-full-lines -check-prefix I386-LINUX %s
-// RUN: %clang_cc1 -x c++ -E -dM -ffreestanding -triple=i386-pc-linux-gnu -target-cpu pentium4 < /dev/null | FileCheck -match-full-lines -check-prefix I386-LINUX -check-prefix I386-LINUX-CXX %s
+// RUN: %clang_cc1 -E -dM -ffreestanding -triple=i386-pc-linux-gnu -target-cpu pentium4 < /dev/null | FileCheck -match-full-lines -check-prefix I386-LINUX -check-prefix I386-LINUX-ALIGN32 %s
+// RUN: %clang_cc1 -x c++ -E -dM -ffreestanding -triple=i386-pc-linux-gnu -target-cpu pentium4 < /dev/null | FileCheck -match-full-lines -check-prefix I386-LINUX -check-prefix I386-LINUX-CXX -check-prefix I386-LINUX-ALIGN32 %s
+// RUN: %clang_cc1 -E -dM -ffreestanding -triple=i386-pc-linux-gnu -target-cpu pentium4 -malign-double < /dev/null | FileCheck -match-full-lines -check-prefix I386-LINUX -check-prefix I386-LINUX-ALIGN64 %s
 //
 // I386-LINUX-NOT:#define _LP64
 // I386-LINUX:#define __BIGGEST_ALIGNMENT__ 16
@@ -2883,6 +2884,18 @@
 // I386-LINUX:#define __FLT_MIN_EXP__ (-125)
 // I386-LINUX:#define __FLT_MIN__ 1.17549435e-38F
 // I386-LINUX:#define __FLT_RADIX__ 2
+// I386-LINUX:#define __GCC_ATOMIC_BOOL_LOCK_FREE 2
+// I386-LINUX:#define __GCC_ATOMIC_CHAR16_T_LOCK_FREE 2
+// I386-LINUX:#define __GCC_ATOMIC_CHAR32_T_LOCK_FREE 2
+// I386-LINUX:#define __GCC_ATOMIC_CHAR_LOCK_FREE 2
+// I386-LINUX:#define __GCC_ATOMIC_INT_LOCK_FREE 2
+// I386-LINUX-ALIGN32:#define __GCC_ATOMIC_LLONG_LOCK_FREE 1
+// I386-LINUX-ALIGN64:#define __GCC_ATOMIC_LLONG_LOCK_FREE 2
+// I386-LINUX:#define __GCC_ATOMIC_LONG_LOCK_FREE 2
+// I386-LINUX:#define __GCC_ATOMIC_POINTER_LOCK_FREE 2
+// I386-LINUX:#define __GCC_ATOMIC_SHORT_LOCK_FREE 2
+// I386-LINUX:#define __GCC_ATOMIC_TEST_AND_SET_TRUEVAL 1
+// I386-LINUX:#define __GCC_ATOMIC_WCHAR_T_LOCK_FREE 2
 // I386-LINUX:#define __INT16_C_SUFFIX__
 // I386-LINUX:#define __INT16_FMTd__ "hd"
 // I386-LINUX:#define __INT16_FMTi__ "hi"
@@ -3034,8 +3047,10 @@
 // I386-LINUX:#define __i386__ 1
 // I386-LINUX:#define i386 1
 //
-// RUN: %clang_cc1 -E -dM -ffreestanding -triple=i386-netbsd < /dev/null | FileCheck -match-full-lines -check-prefix I386-NETBSD %s
-// RUN: %clang_cc1 -x c++ -E -dM -ffreestanding -triple=i386-netbsd < /dev/null | FileCheck -match-full-lines -check-prefix I386-NETBSD -check-prefix I386-NETBSD-CXX %s
+// RUN: %clang_cc1 -E -dM -ffreestanding -triple=i386-netbsd -target-cpu i486 < /dev/null | FileCheck -match-full-lines -check-prefix I386-NETBSD %s
+// RUN: %clang_cc1 -x c++ -E -dM -ffreestanding -triple=i386-netbsd -target-cpu i486 < /dev/null | FileCheck -match-full-lines -check-prefix I386-NETBSD -check-prefix I386-NETBSD-CXX %s
+// RUN: %clang_cc1 -E -dM -ffreestanding -triple=i386-netbsd -target-cpu i486 -malign-double < /dev/null | FileCheck -match-full-lines -check-prefix I386-NETBSD %s
+//
 //
 // I386-NETBSD-NOT:#define _LP64
 // I386-NETBSD:#define __BIGGEST_ALIGNMENT__ 16
@@ -3072,6 +3087,17 @@
 // I386-NETBSD:#define __FLT_MIN_EXP__ (-125)
 // I386-NETBSD:#define __FLT_MIN__ 1.17549435e-38F
 // I386-NETBSD:#define __FLT_RADIX__ 2
+// I386-NETBSD:#define __GCC_ATOMIC_BOOL_LOCK_FREE 2
+// I386-NETBSD:#define __GCC_ATOMIC_CHAR16_T_LOCK_FREE 2
+// I386-NETBSD:#define __GCC_ATOMIC_CHAR32_T_LOCK_FREE 2
+// I386-NETBSD:#define __GCC_ATOMIC_CHAR_LOCK_FREE 2
+// I386-NETBSD:#define __GCC_ATOMIC_INT_LOCK_FREE 2
+// I386-NETBSD:#define __GCC_ATOMIC_LLONG_LOCK_FREE 1
+// I386-NETBSD:#define __GCC_ATOMIC_LONG_LOCK_FREE 2
+// I386-NETBSD:#define __GCC_ATOMIC_POINTER_LOCK_FREE 2
+// I386-NETBSD:#define __GCC_ATOMIC_SHORT_LOCK_FREE 2
+// I386-NETBSD:#define __GCC_ATOMIC_TEST_AND_SET_TRUEVAL 1
+// I386-NETBSD:#define __GCC_ATOMIC_WCHAR_T_LOCK_FREE 2
 // I386-NETBSD:#define __INT16_C_SUFFIX__
 // I386-NETBSD:#define __INT16_FMTd__ "hd"
 // I386-NETBSD:#define __INT16_FMTi__ "hi"
@@ -8947,6 +8973,17 @@
 // X86_64-LINUX:#define __FLT_MIN_EXP__ (-125)
 // X86_64-LINUX:#define __FLT_MIN__ 1.17549435e-38F
 // X86_64-LINUX:#define __FLT_RADIX__ 2
+// X86_64-LINUX:#define __GCC_ATOMIC_BOOL_LOCK_FREE 2
+// X86_64-LINUX:#define __GCC_ATOMIC_CHAR16_T_LOCK_FREE 2
+// X86_64-LINUX:#define __GCC_ATOMIC_CHAR32_T_LOCK_FREE 2
+// X86_64-LINUX:#define __GCC_ATOMIC_CHAR_LOCK_FREE 2
+// X86_64-LINUX:#define __GCC_ATOMIC_INT_LOCK_FREE 2
+// X86_64-LINUX:#define __GCC_ATOMIC_LLONG_LOCK_FREE 2
+// X86_64-LINUX:#define __GCC_ATOMIC_LONG_LOCK_FREE 2
+// X86_64-LINUX:#define __GCC_ATOMIC_POINTER_LOCK_FREE 2
+// X86_64-LINUX:#define __GCC_ATOMIC_SHORT_LOCK_FREE 2
+// X86_64-LINUX:#define __GCC_ATOMIC_TEST_AND_SET_TRUEVAL 1
+// X86_64-LINUX:#define __GCC_ATOMIC_WCHAR_T_LOCK_FREE 2
 // X86_64-LINUX:#define __INT16_C_SUFFIX__
 // X86_64-LINUX:#define __INT16_FMTd__ "hd"
 // X86_64-LINUX:#define __INT16_FMTi__ "hi"
@@ -9149,6 +9186,17 @@
 // X86_64-NETBSD:#define __FLT_MIN_EXP__ (-125)
 // X86_64-NETBSD:#define __FLT_MIN__ 1.17549435e-38F
 // X86_64-NETBSD:#define __FLT_RADIX__ 2
+// X86_64-NETBSD:#define __GCC_ATOMIC_BOOL_LOCK_FREE 2
+// X86_64-NETBSD:#define __GCC_ATOMIC_CHAR16_T_LOCK_FREE 2
+// X86_64-NETBSD:#define __GCC_ATOMIC_CHAR32_T_LOCK_FREE 2
+// X86_64-NETBSD:#define __GCC_ATOMIC_CHAR_LOCK_FREE 2
+// X86_64-NETBSD:#define __GCC_ATOMIC_INT_LOCK_FREE 2
+// X86_64-NETBSD:#define __GCC_ATOMIC_LLONG_LOCK_FREE 2
+// X86_64-NETBSD:#define __GCC_ATOMIC_LONG_LOCK_FREE 2
+// X86_64-NETBSD:#define __GCC_ATOMIC_POINTER_LOCK_FREE 2
+// X86_64-NETBSD:#define __GCC_ATOMIC_SHORT_LOCK_FREE 2
+// X86_64-NETBSD:#define __GCC_ATOMIC_TEST_AND_SET_TRUEVAL 1
+// X86_64-NETBSD:#define __GCC_ATOMIC_WCHAR_T_LOCK_FREE 2
 // X86_64-NETBSD:#define __INT16_C_SUFFIX__
 // X86_64-NETBSD:#define __INT16_FMTd__ "hd"
 // X86_64-NETBSD:#define __INT16_FMTi__ "hi"
Index: cfe/trunk/test/Preprocessor/predefined-win-macros.c
===================================================================
--- cfe/trunk/test/Preprocessor/predefined-win-macros.c
+++ cfe/trunk/test/Preprocessor/predefined-win-macros.c
@@ -3,7 +3,7 @@
 // RUN: %clang_cc1 %s -x c++ -E -dM -triple x86_64-pc-win32 -fms-extensions -fms-compatibility \
 // RUN:     -fms-compatibility-version=19.00 -std=c++14 -o - | FileCheck -match-full-lines %s --check-prefix=CHECK-MS64
 // RUN: %clang_cc1 %s -x c++ -E -dM -triple x86_64-pc-win32 -fms-extensions -fms-compatibility \
-// RUN:     -fms-compatibility-version=19.00 -std=c++14 -o - | grep GCC | count 1
+// RUN:     -fms-compatibility-version=19.00 -std=c++14 -o - | grep GCC | count 5
 // CHECK-MS64: #define _INTEGRAL_MAX_BITS 64
 // CHECK-MS64: #define _MSC_EXTENSIONS 1
 // CHECK-MS64: #define _MSC_VER 1900
@@ -15,13 +15,17 @@
 // CHECK-MS64-NOT: GNU
 // CHECK-MS64-NOT: GXX
 // CHECK-MS64: #define __GCC_ASM_FLAG_OUTPUTS__ 1
+// CHECK-MS64: #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_1 1
+// CHECK-MS64: #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_2 1
+// CHECK-MS64: #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4 1
+// CHECK-MS64: #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_8 1
 // CHECK-MS64-NOT: GNU
 // CHECK-MS64-NOT: GXX
 
 // RUN: %clang_cc1 %s -x c++ -E -dM -triple i686-pc-win32 -fms-extensions -fms-compatibility \
 // RUN:     -fms-compatibility-version=19.00 -std=c++17 -o - | FileCheck -match-full-lines %s --check-prefix=CHECK-MS
 // RUN: %clang_cc1 %s -x c++ -E -dM -triple i686-pc-win32 -fms-extensions -fms-compatibility \
-// RUN:     -fms-compatibility-version=19.00 -std=c++17 -o - | grep GCC | count 1
+// RUN:     -fms-compatibility-version=19.00 -std=c++17 -o - | grep GCC | count 5
 // CHECK-MS: #define _INTEGRAL_MAX_BITS 64
 // CHECK-MS: #define _MSC_EXTENSIONS 1
 // CHECK-MS: #define _MSC_VER 1900
@@ -33,6 +37,10 @@
 // CHECK-MS-NOT: GNU
 // CHECK-MS-NOT: GXX
 // CHECK-MS: #define __GCC_ASM_FLAG_OUTPUTS__ 1
+// CHECK-MS: #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_1 1
+// CHECK-MS: #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_2 1
+// CHECK-MS: #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4 1
+// CHECK-MS: #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_8 1
 // CHECK-MS-NOT: GNU
 // CHECK-MS-NOT: GXX