Index: include/clang/Basic/TokenKinds.def
===================================================================
--- include/clang/Basic/TokenKinds.def
+++ include/clang/Basic/TokenKinds.def
@@ -397,6 +397,7 @@
 KEYWORD(__builtin_va_arg            , KEYALL)
 KEYWORD(__extension__               , KEYALL)
 KEYWORD(__float128                  , KEYALL)
+ALIAS("_Float128", __float128       , KEYALL)
 KEYWORD(__imag                      , KEYALL)
 KEYWORD(__int128                    , KEYALL)
 KEYWORD(__label__                   , KEYALL)
Index: lib/Frontend/InitPreprocessor.cpp
===================================================================
--- lib/Frontend/InitPreprocessor.cpp
+++ lib/Frontend/InitPreprocessor.cpp
@@ -814,6 +814,8 @@
   DefineFloatMacros(Builder, "FLT", &TI.getFloatFormat(), "F");
   DefineFloatMacros(Builder, "DBL", &TI.getDoubleFormat(), "");
   DefineFloatMacros(Builder, "LDBL", &TI.getLongDoubleFormat(), "L");
+  DefineFloatMacros(Builder, "FLT128", &TI.getFloat128Format(), "Q");
+
 
   // Define a __POINTER_WIDTH__ macro for stdint.h.
   Builder.defineMacro("__POINTER_WIDTH__",
Index: test/Preprocessor/cuda-types.cu
===================================================================
--- test/Preprocessor/cuda-types.cu
+++ test/Preprocessor/cuda-types.cu
@@ -9,40 +9,40 @@
 
 // RUN: %clang --cuda-host-only -nocudainc -target i386-unknown-linux-gnu -x cuda -E -dM -o - /dev/null \
 // RUN:   | grep 'define __[^ ]*\(TYPE\|MAX\|SIZEOF|WIDTH\)\|define __GCC_ATOMIC' \
-// RUN:   | grep -v '__LDBL\|_LONG_DOUBLE' > %t/i386-host-defines-filtered
+// RUN:   | grep -v '__FLT128\|__LDBL\|_LONG_DOUBLE' > %t/i386-host-defines-filtered
 // RUN: %clang --cuda-device-only -nocudainc -nocudalib -target i386-unknown-linux-gnu -x cuda -E -dM -o - /dev/null \
 // RUN:   | grep 'define __[^ ]*\(TYPE\|MAX\|SIZEOF|WIDTH\)\|define __GCC_ATOMIC' \
-// RUN:   | grep -v '__LDBL\|_LONG_DOUBLE' > %t/i386-device-defines-filtered
+// RUN:   | grep -v '__FLT128\|__LDBL\|_LONG_DOUBLE' > %t/i386-device-defines-filtered
 // RUN: diff %t/i386-host-defines-filtered %t/i386-device-defines-filtered
 
 // RUN: %clang --cuda-host-only -nocudainc -target x86_64-unknown-linux-gnu -x cuda -E -dM -o - /dev/null \
 // RUN:   | grep 'define __[^ ]*\(TYPE\|MAX\|SIZEOF|WIDTH\)\|define __GCC_ATOMIC' \
-// RUN:   | grep -v '__LDBL\|_LONG_DOUBLE' > %t/x86_64-host-defines-filtered
+// RUN:   | grep -v '__FLT128\|__LDBL\|_LONG_DOUBLE' > %t/x86_64-host-defines-filtered
 // RUN: %clang --cuda-device-only -nocudainc -nocudalib -target x86_64-unknown-linux-gnu -x cuda -E -dM -o - /dev/null \
 // RUN:   | grep 'define __[^ ]*\(TYPE\|MAX\|SIZEOF|WIDTH\)\|define __GCC_ATOMIC' \
-// RUN:   | grep -v '__LDBL\|_LONG_DOUBLE' > %t/x86_64-device-defines-filtered
+// RUN:   | grep -v '__FLT128\|__LDBL\|_LONG_DOUBLE' > %t/x86_64-device-defines-filtered
 // RUN: diff %t/x86_64-host-defines-filtered %t/x86_64-device-defines-filtered
 
 // RUN: %clang --cuda-host-only -nocudainc -target powerpc64-unknown-linux-gnu -x cuda -E -dM -o - /dev/null \
 // RUN:   | grep 'define __[^ ]*\(TYPE\|MAX\|SIZEOF|WIDTH\)\|define __GCC_ATOMIC' \
-// RUN:   | grep -v '__LDBL\|_LONG_DOUBLE' > %t/powerpc64-host-defines-filtered
+// RUN:   | grep -v '__FLT128\|__LDBL\|_LONG_DOUBLE' > %t/powerpc64-host-defines-filtered
 // RUN: %clang --cuda-device-only -nocudainc -nocudalib -target powerpc64-unknown-linux-gnu -x cuda -E -dM -o - /dev/null \
 // RUN:   | grep 'define __[^ ]*\(TYPE\|MAX\|SIZEOF|WIDTH\)\|define __GCC_ATOMIC' \
-// RUN:   | grep -v '__LDBL\|_LONG_DOUBLE' > %t/powerpc64-device-defines-filtered
+// RUN:   | grep -v '__FLT128\|__LDBL\|_LONG_DOUBLE' > %t/powerpc64-device-defines-filtered
 // RUN: diff %t/powerpc64-host-defines-filtered %t/powerpc64-device-defines-filtered
 
 // RUN: %clang --cuda-host-only -nocudainc -target i386-windows-msvc -x cuda -E -dM -o - /dev/null \
 // RUN:   | grep 'define __[^ ]*\(TYPE\|MAX\|SIZEOF|WIDTH\)\|define __GCC_ATOMIC' \
-// RUN:   | grep -v '__LDBL\|_LONG_DOUBLE' > %t/i386-msvc-host-defines-filtered
+// RUN:   | grep -v '__FLT128\|__LDBL\|_LONG_DOUBLE' > %t/i386-msvc-host-defines-filtered
 // RUN: %clang --cuda-device-only -nocudainc -nocudalib -target i386-windows-msvc -x cuda -E -dM -o - /dev/null \
 // RUN:   | grep 'define __[^ ]*\(TYPE\|MAX\|SIZEOF|WIDTH\)\|define __GCC_ATOMIC' \
-// RUN:   | grep -v '__LDBL\|_LONG_DOUBLE' > %t/i386-msvc-device-defines-filtered
+// RUN:   | grep -v '__FLT128\|__LDBL\|_LONG_DOUBLE' > %t/i386-msvc-device-defines-filtered
 // RUN: diff %t/i386-msvc-host-defines-filtered %t/i386-msvc-device-defines-filtered
 
 // RUN: %clang --cuda-host-only -nocudainc -target x86_64-windows-msvc -x cuda -E -dM -o - /dev/null \
 // RUN:   | grep 'define __[^ ]*\(TYPE\|MAX\|SIZEOF|WIDTH\)\|define __GCC_ATOMIC' \
-// RUN:   | grep -v '__LDBL\|_LONG_DOUBLE' > %t/x86_64-msvc-host-defines-filtered
+// RUN:   | grep -v '__FLT128\|__LDBL\|_LONG_DOUBLE' > %t/x86_64-msvc-host-defines-filtered
 // RUN: %clang --cuda-device-only -nocudainc -nocudalib -target x86_64-windows-msvc -x cuda -E -dM -o - /dev/null \
 // RUN:   | grep 'define __[^ ]*\(TYPE\|MAX\|SIZEOF|WIDTH\)\|define __GCC_ATOMIC' \
-// RUN:   | grep -v '__LDBL\|_LONG_DOUBLE' > %t/x86_64-msvc-device-defines-filtered
+// RUN:   | grep -v '__FLT128\|__LDBL\|_LONG_DOUBLE' > %t/x86_64-msvc-device-defines-filtered
 // RUN: diff %t/x86_64-msvc-host-defines-filtered %t/x86_64-msvc-device-defines-filtered
Index: test/Sema/_Float128.cpp
===================================================================
--- /dev/null
+++ test/Sema/_Float128.cpp
@@ -0,0 +1,38 @@
+// RUN: %clang_cc1 -verify -std=gnu++11 %s
+// RUN: %clang_cc1 -verify -std=c++11 %s
+// RUN: %clang_cc1 -triple powerpc64-linux -verify -std=c++11 %s
+// RUN: %clang_cc1 -triple i686-windows-gnu -verify -std=c++11 %s
+// RUN: %clang_cc1 -triple x86_64-windows-gnu -verify -std=c++11 %s
+// RUN: %clang_cc1 -triple x86_64-windows-msvc -verify -std=c++11 %s
+
+#if defined(__FLOAT128__) || defined(__SIZEOF_FLOAT128__)
+_Float128 f;
+_Float128 tiny = __FLT128_EPSILON__;
+template<typename> struct __is_floating_point_helper {};
+template<> struct __is_floating_point_helper<_Float128> {};
+int g(int x, _Float128 *y) {
+  return x + *y;
+}
+
+// expected-no-diagnostics
+#else
+#if !defined(__STRICT_ANSI__)
+_Float128 f;  // expected-error {{__float128 is not supported on this target}}
+template<typename> struct __is_floating_point_helper {};
+template<> struct __is_floating_point_helper<_Float128> {};  // expected-error {{__float128 is not supported on this target}}
+
+int g(int x, _Float128 *y) {  // expected-error {{__float128 is not supported on this target}}
+  return x + *y;
+}
+
+#else
+_Float128 f;  // expected-error {{__float128 is not supported on this target}}
+template<typename> struct __is_floating_point_helper {};
+template<> struct __is_floating_point_helper<_Float128> {};  // expected-error {{__float128 is not supported on this target}}
+
+int g(int x, _Float128 *y) {  // expected-error {{__float128 is not supported on this target}}
+  return x + *y;
+}
+
+#endif  // !defined(__STRICT_ANSI__)
+#endif  // defined(__FLOAT128__) || defined(__SIZEOF_FLOAT128__)