diff --git a/clang/lib/Basic/Targets/X86.cpp b/clang/lib/Basic/Targets/X86.cpp
--- a/clang/lib/Basic/Targets/X86.cpp
+++ b/clang/lib/Basic/Targets/X86.cpp
@@ -560,6 +560,8 @@
   if (HasVPCLMULQDQ)
     Builder.defineMacro("__VPCLMULQDQ__");
 
+  if (HasLAHFSAHF)
+    Builder.defineMacro("__LAHF_SAHF__");
   if (HasLZCNT)
     Builder.defineMacro("__LZCNT__");
 
diff --git a/clang/test/Preprocessor/predefined-arch-macros.c b/clang/test/Preprocessor/predefined-arch-macros.c
--- a/clang/test/Preprocessor/predefined-arch-macros.c
+++ b/clang/test/Preprocessor/predefined-arch-macros.c
@@ -541,6 +541,7 @@
 // CHECK_CORE_AVX2_M32: #define __F16C__ 1
 // CHECK_CORE_AVX2_M32: #define __FMA__ 1
 // CHECK_CORE_AVX2_M32: #define __INVPCID__ 1
+// CHECK_CORE_AVX2_M32: #define __LAHF_SAHF__ 1
 // CHECK_CORE_AVX2_M32: #define __LZCNT__ 1
 // CHECK_CORE_AVX2_M32: #define __MMX__ 1
 // CHECK_CORE_AVX2_M32: #define __MOVBE__ 1
@@ -572,6 +573,7 @@
 // CHECK_CORE_AVX2_M64: #define __F16C__ 1
 // CHECK_CORE_AVX2_M64: #define __FMA__ 1
 // CHECK_CORE_AVX2_M64: #define __INVPCID__ 1
+// CHECK_CORE_AVX2_M64: #define __LAHF_SAHF__ 1
 // CHECK_CORE_AVX2_M64: #define __LZCNT__ 1
 // CHECK_CORE_AVX2_M64: #define __MMX__ 1
 // CHECK_CORE_AVX2_M64: #define __MOVBE__ 1
@@ -607,6 +609,7 @@
 // CHECK_BROADWELL_M32: #define __F16C__ 1
 // CHECK_BROADWELL_M32: #define __FMA__ 1
 // CHECK_BROADWELL_M32: #define __INVPCID__ 1
+// CHECK_BROADWELL_M32: #define __LAHF_SAHF__ 1
 // CHECK_BROADWELL_M32: #define __LZCNT__ 1
 // CHECK_BROADWELL_M32: #define __MMX__ 1
 // CHECK_BROADWELL_M32: #define __MOVBE__ 1
@@ -641,6 +644,7 @@
 // CHECK_BROADWELL_M64: #define __F16C__ 1
 // CHECK_BROADWELL_M64: #define __FMA__ 1
 // CHECK_BROADWELL_M64: #define __INVPCID__ 1
+// CHECK_BROADWELL_M64: #define __LAHF_SAHF__ 1
 // CHECK_BROADWELL_M64: #define __LZCNT__ 1
 // CHECK_BROADWELL_M64: #define __MMX__ 1
 // CHECK_BROADWELL_M64: #define __MOVBE__ 1
@@ -2515,6 +2519,7 @@
 // RUN:   | FileCheck -match-full-lines %s -check-prefix=CHECK_AMDFAM10_M32
 // CHECK_AMDFAM10_M32: #define __3dNOW_A__ 1
 // CHECK_AMDFAM10_M32: #define __3dNOW__ 1
+// CHECK_AMDFAM10_M32: #define __LAHF_SAHF__ 1
 // CHECK_AMDFAM10_M32: #define __LZCNT__ 1
 // CHECK_AMDFAM10_M32: #define __MMX__ 1
 // CHECK_AMDFAM10_M32: #define __POPCNT__ 1
@@ -2538,6 +2543,7 @@
 // CHECK_AMDFAM10_M64: #define __3dNOW_A__ 1
 // CHECK_AMDFAM10_M64: #define __3dNOW__ 1
 // CHECK_AMDFAM10_M64: #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_16 1
+// CHECK_AMDFAM10_M64: #define __LAHF_SAHF__ 1
 // CHECK_AMDFAM10_M64: #define __LZCNT__ 1
 // CHECK_AMDFAM10_M64: #define __MMX__ 1
 // CHECK_AMDFAM10_M64: #define __POPCNT__ 1
@@ -2562,6 +2568,7 @@
 // RUN:   | FileCheck -match-full-lines %s -check-prefix=CHECK_BTVER1_M32
 // CHECK_BTVER1_M32-NOT: #define __3dNOW_A__ 1
 // CHECK_BTVER1_M32-NOT: #define __3dNOW__ 1
+// CHECK_BTVER1_M32: #define __LAHF_SAHF__ 1
 // CHECK_BTVER1_M32: #define __LZCNT__ 1
 // CHECK_BTVER1_M32: #define __MMX__ 1
 // CHECK_BTVER1_M32: #define __POPCNT__ 1
@@ -2584,6 +2591,7 @@
 // RUN:   | FileCheck -match-full-lines %s -check-prefix=CHECK_BTVER1_M64
 // CHECK_BTVER1_M64-NOT: #define __3dNOW_A__ 1
 // CHECK_BTVER1_M64-NOT: #define __3dNOW__ 1
+// CHECK_BTVER1_M64: #define __LAHF_SAHF__ 1
 // CHECK_BTVER1_M64: #define __LZCNT__ 1
 // CHECK_BTVER1_M64: #define __MMX__ 1
 // CHECK_BTVER1_M64: #define __POPCNT__ 1
@@ -3023,6 +3031,7 @@
 // CHECK_ZNVER1_M64-NOT: #define __FMA4__ 1
 // CHECK_ZNVER1_M64: #define __FMA__ 1
 // CHECK_ZNVER1_M64: #define __FSGSBASE__ 1
+// CHECK_ZNVER1_M64: #define __LAHF_SAHF__ 1
 // CHECK_ZNVER1_M64: #define __LZCNT__ 1
 // CHECK_ZNVER1_M64: #define __MMX__ 1
 // CHECK_ZNVER1_M64: #define __MOVBE__ 1
@@ -3073,6 +3082,7 @@
 // CHECK_ZNVER2_M32-NOT: #define __FMA4__ 1
 // CHECK_ZNVER2_M32: #define __FMA__ 1
 // CHECK_ZNVER2_M32: #define __FSGSBASE__ 1
+// CHECK_ZNVER2_M32: #define __LAHF_SAHF__ 1
 // CHECK_ZNVER2_M32: #define __LZCNT__ 1
 // CHECK_ZNVER2_M32: #define __MMX__ 1
 // CHECK_ZNVER2_M32: #define __PCLMUL__ 1
@@ -3122,6 +3132,7 @@
 // CHECK_ZNVER2_M64-NOT: #define __FMA4__ 1
 // CHECK_ZNVER2_M64: #define __FMA__ 1
 // CHECK_ZNVER2_M64: #define __FSGSBASE__ 1
+// CHECK_ZNVER2_M64: #define __LAHF_SAHF__ 1
 // CHECK_ZNVER2_M64: #define __LZCNT__ 1
 // CHECK_ZNVER2_M64: #define __MMX__ 1
 // CHECK_ZNVER2_M64: #define __PCLMUL__ 1