Index: include/clang/Basic/Builtins.def
===================================================================
--- include/clang/Basic/Builtins.def
+++ include/clang/Basic/Builtins.def
@@ -1067,9 +1067,10 @@
 LIBBUILTIN(floorf, "ff", "fnc", "math.h", ALL_LANGUAGES)
 LIBBUILTIN(floorl, "LdLd", "fnc", "math.h", ALL_LANGUAGES)
 
-LIBBUILTIN(fma, "dddd", "fne", "math.h", ALL_LANGUAGES)
-LIBBUILTIN(fmaf, "ffff", "fne", "math.h", ALL_LANGUAGES)
-LIBBUILTIN(fmal, "LdLdLdLd", "fne", "math.h", ALL_LANGUAGES)
+// Posix standard says this updates errno, but we always emit an intrinsic.
+LIBBUILTIN(fma, "dddd", "fnc", "math.h", ALL_LANGUAGES)
+LIBBUILTIN(fmaf, "ffff", "fnc", "math.h", ALL_LANGUAGES)
+LIBBUILTIN(fmal, "LdLdLdLd", "fnc", "math.h", ALL_LANGUAGES)
 
 LIBBUILTIN(fmax, "ddd", "fnc", "math.h", ALL_LANGUAGES)
 LIBBUILTIN(fmaxf, "fff", "fnc", "math.h", ALL_LANGUAGES)
Index: lib/CodeGen/CGBuiltin.cpp
===================================================================
--- lib/CodeGen/CGBuiltin.cpp
+++ lib/CodeGen/CGBuiltin.cpp
@@ -1898,6 +1898,8 @@
   case Builtin::BI__builtin_fmaf:
   case Builtin::BI__builtin_fmal: {
     // Rewrite fma to intrinsic.
+    if (!FD->hasAttr<ConstAttr>())
+      break;
     Value *FirstArg = EmitScalarExpr(E->getArg(0));
     llvm::Type *ArgType = FirstArg->getType();
     Value *F = CGM.getIntrinsic(Intrinsic::fma, ArgType);