Index: include/clang/Basic/TargetInfo.h
===================================================================
--- include/clang/Basic/TargetInfo.h
+++ include/clang/Basic/TargetInfo.h
@@ -58,6 +58,7 @@
   bool BigEndian;
   bool TLSSupported;
   bool NoAsmVariants;  // True if {|} are normal characters.
+  bool HasFloat128;
   unsigned char PointerWidth, PointerAlign;
   unsigned char BoolWidth, BoolAlign;
   unsigned char IntWidth, IntAlign;
@@ -329,9 +330,7 @@
   } // FIXME
 
   /// \brief Determine whether the __float128 type is supported on this target.
-  virtual bool hasFloat128Type() const {
-    return false;
-  }
+  virtual bool hasFloat128Type() const { return HasFloat128; }
 
   /// \brief Return the alignment that is suitable for storing any
   /// object with a fundamental alignment requirement.
Index: lib/Basic/TargetInfo.cpp
===================================================================
--- lib/Basic/TargetInfo.cpp
+++ lib/Basic/TargetInfo.cpp
@@ -30,6 +30,7 @@
   BigEndian = true;
   TLSSupported = true;
   NoAsmVariants = false;
+  HasFloat128 = false;
   PointerWidth = PointerAlign = 32;
   BoolWidth = BoolAlign = 8;
   IntWidth = IntAlign = 32;
Index: lib/Basic/Targets.cpp
===================================================================
--- lib/Basic/Targets.cpp
+++ lib/Basic/Targets.cpp
@@ -434,6 +434,11 @@
     case llvm::Triple::ppc64le:
       this->MCountName = "_mcount";
       break;
+    case llvm::Triple::x86:
+    case llvm::Triple::x86_64:
+    case llvm::Triple::systemz:
+      this->HasFloat128 = true;
+      break;
     }
   }
 
@@ -806,7 +811,6 @@
   bool HasHTM;
   bool HasBPERMD;
   bool HasExtDiv;
-  bool HasFloat128;
 
 protected:
   std::string ABI;
@@ -815,7 +819,7 @@
   PPCTargetInfo(const llvm::Triple &Triple, const TargetOptions &)
     : TargetInfo(Triple), HasVSX(false), HasP8Vector(false),
       HasP8Crypto(false), HasDirectMove(false), HasQPX(false), HasHTM(false),
-      HasBPERMD(false), HasExtDiv(false), HasFloat128(false) {
+      HasBPERMD(false), HasExtDiv(false) {
     BigEndian = (Triple.getArch() != llvm::Triple::ppc64le);
     SimdDefaultAlign = 128;
     LongDoubleWidth = LongDoubleAlign = 128;
@@ -1059,9 +1063,6 @@
            LongDoubleFormat == &llvm::APFloat::PPCDoubleDouble &&
            getTriple().isOSBinFormatELF();
   }
-  bool hasFloat128Type() const override {
-    return HasFloat128;
-  }
 };
 
 const Builtin::Info PPCTargetInfo::BuiltinInfo[] = {
Index: test/CodeGenCXX/float128-declarations.cpp
===================================================================
--- test/CodeGenCXX/float128-declarations.cpp
+++ test/CodeGenCXX/float128-declarations.cpp
@@ -2,8 +2,16 @@
 // RUN:   -target-feature +float128 -std=c++11 %s -o - | FileCheck %s
 // RUN: %clang_cc1 -emit-llvm -triple powerpc64le-unknown-unknown \
 // RUN:   -target-feature +float128 -std=c++11 %s -o - | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm -triple i386-unknown-linux-gnu -std=c++11 \
+// RUN:   %s -o - | FileCheck %s -check-prefix=CHECK-X86
+// RUN: %clang_cc1 -emit-llvm -triple x86_64-unknown-linux-gnu -std=c++11 \
+// RUN:   %s -o - | FileCheck %s -check-prefix=CHECK-X86
+// RUN: %clang_cc1 -emit-llvm -triple systemz-unknown-linux-gnu -std=c++11 \
+// RUN:   %s -o - | FileCheck %s -check-prefix=CHECK-SYSZ
 //
-/*  Various contexts where type __float128 can appear. */
+/*  Various contexts where type __float128 can appear. The different check
+    prefixes are due to different mangling on X86 and different calling
+    convention on SystemZ. */
 
 /*  Namespace */
 namespace {
@@ -84,3 +92,47 @@
 // CHECK-DAG: [[F4L:%[a-z0-9]+]] = load fp128, fp128* %f4l
 // CHECK-DAG: [[INC:%[a-z0-9]+]] = fadd fp128 [[F4L]], 0xL00000000000000003FFF000000000000
 // CHECK-DAG: store fp128 [[INC]], fp128* %f4l
+
+// CHECK-X86-DAG: @_ZN12_GLOBAL__N_13f1nE = internal global fp128 0xL00000000000000000000000000000000
+// CHECK-X86-DAG: @_ZN12_GLOBAL__N_13f2nE = internal global fp128 0xL00000000000000004004080000000000
+// CHECK-X86-DAG: @_ZN12_GLOBAL__N_15arr1nE = internal global [10 x fp128]
+// CHECK-X86-DAG: @_ZN12_GLOBAL__N_15arr2nE = internal global [3 x fp128] [fp128 0xL33333333333333333FFF333333333333, fp128 0xL00000000000000004000800000000000, fp128 0xL00000000000000004025176592E00000]
+// CHECK-X86-DAG: define internal fp128 @_ZN12_GLOBAL__N_16func1nERKg(fp128*
+// CHECK-X86-DAG: @f1f = global fp128 0xL00000000000000000000000000000000
+// CHECK-X86-DAG: @f2f = global fp128 0xL33333333333333334004033333333333
+// CHECK-X86-DAG: @arr1f = global [10 x fp128]
+// CHECK-X86-DAG: @arr2f = global [3 x fp128] [fp128 0xL3333333333333333BFFF333333333333, fp128 0xL0000000000000000C000800000000000, fp128 0xL0000000000000000C025176592E00000]
+// CHECK-X86-DAG: declare fp128 @_Z6func1fg(fp128)
+// CHECK-X86-DAG: define linkonce_odr void @_ZN2C1C2Eg(%class.C1* %this, fp128 %arg)
+// CHECK-X86-DAG: define linkonce_odr fp128 @_ZN2C16func2cEg(fp128 %arg)
+// CHECK-X86-DAG: define linkonce_odr fp128 @_Z6func1tIgET_S0_(fp128 %arg)
+// CHECK-X86-DAG: @_ZZ4mainE2s1 = private unnamed_addr constant %struct.S1 { fp128 0xL00000000000000004006080000000000 }
+// CHECK-X86-DAG: store fp128 0xLF0AFD0EBFF292DCE42E0B38CDD83F26F, fp128* %f1l, align 16
+// CHECK-X86-DAG: store fp128 0xL00000000000000008000000000000000, fp128* %f2l, align 16
+// CHECK-X86-DAG: store fp128 0xLFFFFFFFFFFFFFFFF7FFEFFFFFFFFFFFF, fp128* %f3l, align 16
+// CHECK-X86-DAG: store fp128 0xL0000000000000000BFFF000000000000, fp128* %f5l, align 16
+// CHECK-X86-DAG: [[F4L:%[a-z0-9]+]] = load fp128, fp128* %f4l
+// CHECK-X86-DAG: [[INC:%[a-z0-9]+]] = fadd fp128 [[F4L]], 0xL00000000000000003FFF000000000000
+// CHECK-X86-DAG: store fp128 [[INC]], fp128* %f4l
+
+// CHECK-SYSZ-DAG: @_ZN12_GLOBAL__N_13f1nE = internal global fp128 0xL00000000000000000000000000000000
+// CHECK-SYSZ-DAG: @_ZN12_GLOBAL__N_13f2nE = internal global fp128 0xL00000000000000004004080000000000
+// CHECK-SYSZ-DAG: @_ZN12_GLOBAL__N_15arr1nE = internal global [10 x fp128]
+// CHECK-SYSZ-DAG: @_ZN12_GLOBAL__N_15arr2nE = internal global [3 x fp128] [fp128 0xL33333333333333333FFF333333333333, fp128 0xL00000000000000004000800000000000, fp128 0xL00000000000000004025176592E00000]
+// CHECK-SYSZ-DAG: define internal void @_ZN12_GLOBAL__N_16func1nERKU10__float128(fp128*
+// CHECK-SYSZ-DAG: @f1f = global fp128 0xL00000000000000000000000000000000
+// CHECK-SYSZ-DAG: @f2f = global fp128 0xL33333333333333334004033333333333
+// CHECK-SYSZ-DAG: @arr1f = global [10 x fp128]
+// CHECK-SYSZ-DAG: @arr2f = global [3 x fp128] [fp128 0xL3333333333333333BFFF333333333333, fp128 0xL0000000000000000C000800000000000, fp128 0xL0000000000000000C025176592E00000]
+// CHECK-SYSZ-DAG: declare void @_Z6func1fU10__float128(fp128*
+// CHECK-SYSZ-DAG: define linkonce_odr void @_ZN2C1C2EU10__float128(%class.C1* %this, fp128*
+// CHECK-SYSZ-DAG: define linkonce_odr void @_ZN2C16func2cEU10__float128(fp128*
+// CHECK-SYSZ-DAG: define linkonce_odr void @_Z6func1tIU10__float128ET_S0_(fp128*
+// CHECK-SYSZ-DAG: @_ZZ4mainE2s1 = private unnamed_addr constant %struct.S1 { fp128 0xL00000000000000004006080000000000 }
+// CHECK-SYSZ-DAG: store fp128 0xLF0AFD0EBFF292DCE42E0B38CDD83F26F, fp128* %f1l, align 16
+// CHECK-SYSZ-DAG: store fp128 0xL00000000000000008000000000000000, fp128* %f2l, align 16
+// CHECK-SYSZ-DAG: store fp128 0xLFFFFFFFFFFFFFFFF7FFEFFFFFFFFFFFF, fp128* %f3l, align 16
+// CHECK-SYSZ-DAG: store fp128 0xL0000000000000000BFFF000000000000, fp128* %f5l, align 16
+// CHECK-SYSZ-DAG: [[F4L:%[a-z0-9]+]] = load fp128, fp128* %f4l
+// CHECK-SYSZ-DAG: [[INC:%[a-z0-9]+]] = fadd fp128 [[F4L]], 0xL00000000000000003FFF000000000000
+// CHECK-SYSZ-DAG: store fp128 [[INC]], fp128* %f4l
Index: test/Sema/128bitfloat.cpp
===================================================================
--- test/Sema/128bitfloat.cpp
+++ test/Sema/128bitfloat.cpp
@@ -1,6 +1,16 @@
 // RUN: %clang_cc1 -fsyntax-only -verify -std=gnu++11 %s
 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
 
+#ifdef __x86_64__
+__float128 f;
+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}}
 // But this should work:
@@ -22,3 +32,4 @@
 }
 
 #endif
+#endif
Index: test/Sema/attr-mode.c
===================================================================
--- test/Sema/attr-mode.c
+++ test/Sema/attr-mode.c
@@ -76,7 +76,7 @@
 void test_long_to_i64(long* y) { f_i64_arg(y); }
 void test_long_to_ui64(unsigned long* y) { f_ui64_arg(y); }
 #endif
-typedef          float f128ibm __attribute__ ((mode (TF)));     // expected-error{{unsupported machine mode 'TF'}}
+typedef          float f128ibm __attribute__ ((mode (TF)));
 #elif TEST_64BIT_PPC64
 typedef          float f128ibm __attribute__ ((mode (TF)));
 typedef _Complex float c128ibm __attribute__ ((mode (TC)));