Index: include/clang/Basic/LangOptions.def
===================================================================
--- include/clang/Basic/LangOptions.def
+++ include/clang/Basic/LangOptions.def
@@ -146,6 +146,7 @@
 COMPATIBLE_LANGOPT(Deprecated        , 1, 0, "__DEPRECATED predefined macro")
 LANGOPT(FastMath          , 1, 0, "__FAST_MATH__ predefined macro")
 LANGOPT(FiniteMathOnly    , 1, 0, "__FINITE_MATH_ONLY__ predefined macro")
+LANGOPT(UnsafeFPMath      , 1, 0, "Unsafe Floating Point Math")
 
 BENIGN_LANGOPT(ObjCGCBitmapPrint , 1, 0, "printing of GC's bitmap layout for __weak/__strong ivars")
 
Index: lib/Basic/Targets.cpp
===================================================================
--- lib/Basic/Targets.cpp
+++ lib/Basic/Targets.cpp
@@ -4762,6 +4762,9 @@
     // ACLE 6.4.6 Q (saturation) flag
     if (hasDSP || hasSAT)
       Builder.defineMacro("__ARM_FEATURE_QBIT", "1");
+
+    if (Opts.UnsafeFPMath)
+      Builder.defineMacro("__ARM_FP_FAST", "1");
   }
 
   void getTargetBuiltins(const Builtin::Info *&Records,
@@ -5215,7 +5218,7 @@
     Builder.defineMacro("__ARM_ARCH_PROFILE", "'A'");
 
     Builder.defineMacro("__ARM_64BIT_STATE", "1");
-    Builder.defineMacro("__ARM_PCS_AAPCS64");
+    Builder.defineMacro("__ARM_PCS_AAPCS64", "1");
     Builder.defineMacro("__ARM_ARCH_ISA_A64", "1");
 
     Builder.defineMacro("__ARM_FEATURE_CLZ", "1");
@@ -5236,11 +5239,8 @@
     Builder.defineMacro("__ARM_FP16_FORMAT_IEEE", "1");
     Builder.defineMacro("__ARM_FP16_ARGS", "1");
 
-    if (Opts.FastMath || Opts.FiniteMathOnly)
-      Builder.defineMacro("__ARM_FP_FAST");
-
-    if (Opts.C99 && !Opts.Freestanding)
-      Builder.defineMacro("__ARM_FP_FENV_ROUNDING");
+    if (Opts.UnsafeFPMath)
+      Builder.defineMacro("__ARM_FP_FAST", "1");
 
     Builder.defineMacro("__ARM_SIZEOF_WCHAR_T", Opts.ShortWChar ? "2" : "4");
 
Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp
+++ lib/Frontend/CompilerInvocation.cpp
@@ -1708,6 +1708,9 @@
   Opts.FiniteMathOnly = Args.hasArg(OPT_ffinite_math_only) ||
       Args.hasArg(OPT_cl_finite_math_only) ||
       Args.hasArg(OPT_cl_fast_relaxed_math);
+  Opts.UnsafeFPMath = Args.hasArg(OPT_menable_unsafe_fp_math) ||
+                      Args.hasArg(OPT_cl_unsafe_math_optimizations) ||
+                      Args.hasArg(OPT_cl_fast_relaxed_math);
 
   Opts.RetainCommentsFromSystemHeaders =
       Args.hasArg(OPT_fretain_comments_from_system_headers);
Index: test/Preprocessor/aarch64-target-features.c
===================================================================
--- test/Preprocessor/aarch64-target-features.c
+++ test/Preprocessor/aarch64-target-features.c
@@ -30,10 +30,11 @@
 // CHECK: __ARM_FP16_ARGS 1
 // CHECK: __ARM_FP16_FORMAT_IEEE 1
 // CHECK-NOT: __ARM_FP_FAST 1
-// CHECK: __ARM_FP_FENV_ROUNDING 1
 // CHECK: __ARM_NEON 1
 // CHECK: __ARM_NEON_FP 0xE
 // CHECK: __ARM_PCS_AAPCS64 1
+// CHECK-NOT: __ARM_PCS 1
+// CHECK-NOT: __ARM_PCS_VFP 1
 // CHECK-NOT: __ARM_SIZEOF_MINIMAL_ENUM 1
 // CHECK-NOT: __ARM_SIZEOF_WCHAR_T 2
 
@@ -50,6 +51,9 @@
 // RUN: %clang -target arm64-none-linux-gnu -march=armv8-a+crc -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-CRC32 %s
 // CHECK-CRC32: __ARM_FEATURE_CRC32 1
 
+// RUN: %clang -target aarch64-none-linux-gnu -fno-math-errno -fno-signed-zeros\
+// RUN:        -fno-trapping-math -fassociative-math -freciprocal-math\
+// RUN:        -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-FASTMATH %s
 // RUN: %clang -target aarch64-none-linux-gnu -ffast-math -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-FASTMATH %s
 // RUN: %clang -target arm64-none-linux-gnu -ffast-math -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-FASTMATH %s
 // CHECK-FASTMATH: __ARM_FP_FAST 1
Index: test/Preprocessor/arm-target-features.c
===================================================================
--- test/Preprocessor/arm-target-features.c
+++ test/Preprocessor/arm-target-features.c
@@ -32,6 +32,7 @@
 // CHECK-V8-BAREHF: __ARM_FEATURE_DIRECTED_ROUNDING 1
 // CHECK-V8-BAREHF: __ARM_FEATURE_NUMERIC_MAXMIN 1
 // CHECK-V8-BAREHF: __ARM_NEON__ 1
+// CHECK-V8-BAREHF: __ARM_PCS_VFP 1
 // CHECK-V8-BAREHF: __VFP_FP__ 1
 
 // RUN: %clang -target armv8a -mfloat-abi=hard -mfpu=fp-armv8 -x c -E -dM %s | FileCheck --check-prefix=CHECK-V8-BAREHF-FP %s
@@ -85,9 +86,17 @@
 // THUMBV8A-EABI:#define __ARM_ARCH_EXT_IDIV__ 1
 
 // RUN: %clang -target arm-none-linux-gnu -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-DEFS %s
+// CHECK-DEFS:#define __ARM_PCS 1
 // CHECK-DEFS:#define __ARM_SIZEOF_MINIMAL_ENUM 4
 // CHECK-DEFS:#define __ARM_SIZEOF_WCHAR_T 4
 
+// RUN: %clang -target arm-none-linux-gnu -fno-math-errno -fno-signed-zeros\
+// RUN:        -fno-trapping-math -fassociative-math -freciprocal-math\
+// RUN:        -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-FASTMATH %s
+// RUN: %clang -target arm-none-linux-gnu -ffast-math -x c -E -dM %s -o -\
+// RUN:        | FileCheck --check-prefix=CHECK-FASTMATH %s
+// CHECK-FASTMATH: __ARM_FP_FAST 1
+
 // RUN: %clang -target arm-none-linux-gnu -fshort-wchar -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-SHORTWCHAR %s
 // CHECK-SHORTWCHAR:#define __ARM_SIZEOF_WCHAR_T 2