Index: lib/Basic/Targets/AMDGPU.cpp
===================================================================
--- lib/Basic/Targets/AMDGPU.cpp
+++ lib/Basic/Targets/AMDGPU.cpp
@@ -341,4 +341,9 @@
     Builder.defineMacro("__HAS_LDEXPF__");
   if (hasFP64)
     Builder.defineMacro("__HAS_FP64__");
+
+  if (getTriple().getArch() == llvm::Triple::amdgcn) {
+    Builder.defineMacro("FP_FAST_FMA");
+    Builder.defineMacro("FP_FAST_FMAF");
+  }
 }
Index: test/Driver/amdgpu-macros.cl
===================================================================
--- test/Driver/amdgpu-macros.cl
+++ test/Driver/amdgpu-macros.cl
@@ -92,6 +92,9 @@
 // ARCH-GCN-DAG: #define __AMDGPU__ 1
 // ARCH-GCN-DAG: #define __AMDGCN__ 1
 
+// ARCH-GCN-DAG: #define FP_FAST_FMA 1
+// ARCH-GCN-DAG: #define FP_FAST_FMAF 1
+
 // GFX600: #define __gfx600__ 1
 // GFX601: #define __gfx601__ 1
 // GFX700: #define __gfx700__ 1