Index: cfe/trunk/lib/Basic/TargetInfo.cpp
===================================================================
--- cfe/trunk/lib/Basic/TargetInfo.cpp
+++ cfe/trunk/lib/Basic/TargetInfo.cpp
@@ -45,7 +45,7 @@
   // From the glibc documentation, on GNU systems, malloc guarantees 16-byte
   // alignment on 64-bit systems and 8-byte alignment on 32-bit systems. See
   // https://www.gnu.org/software/libc/manual/html_node/Malloc-Examples.html
-  if (T.isGNUEnvironment())
+  if (T.isGNUEnvironment() || T.isWindowsMSVCEnvironment())
     NewAlign = Triple.isArch64Bit() ? 128 : Triple.isArch32Bit() ? 64 : 0;
   else
     NewAlign = 0; // Infer from basic type alignment.
Index: cfe/trunk/test/CodeGenCXX/cxx1z-aligned-allocation.cpp
===================================================================
--- cfe/trunk/test/CodeGenCXX/cxx1z-aligned-allocation.cpp
+++ cfe/trunk/test/CodeGenCXX/cxx1z-aligned-allocation.cpp
@@ -4,6 +4,8 @@
 // RUN: %clang_cc1 -std=c++14 -fexceptions -fsized-deallocation -faligned-allocation %s -emit-llvm -triple x86_64-linux-gnu -o - | FileCheck %s
 // RUN: %clang_cc1 -std=c++1z -fexceptions -fsized-deallocation %s -emit-llvm -triple x86_64-linux-gnu -o - | FileCheck %s
 
+// RUN: %clang_cc1 -std=c++1z -fexceptions -fsized-deallocation %s -emit-llvm -triple x86_64-windows-msvc -o - | FileCheck %s --check-prefix=CHECK-MS
+
 // Check that we don't used aligned (de)allocation without -faligned-allocation or C++1z.
 // RUN: %clang_cc1 -std=c++14 -DUNALIGNED -fexceptions %s -emit-llvm -triple x86_64-linux-gnu -o - | FileCheck %s --check-prefix=CHECK-UNALIGNED
 // RUN: %clang_cc1 -std=c++1z -DUNALIGNED -fexceptions -fno-aligned-allocation %s -emit-llvm -triple x86_64-linux-gnu -o - | FileCheck %s --check-prefix=CHECK-UNALIGNED
@@ -27,14 +29,28 @@
 // CHECK-LABEL: define {{.*}} @_Z2a0v()
 // CHECK: %[[ALLOC:.*]] = call i8* @_ZnwmSt11align_val_t(i64 512, i64 32)
 // CHECK: call void @_ZdlPvSt11align_val_t(i8* %[[ALLOC]], i64 32)
+// CHECK-MS-LABEL: define {{.*}} @"\01?a0@@YAPEAXXZ"()
+// CHECK-MS: %[[ALLOC:.*]] = call i8* @"\01??2@YAPEAX_KW4align_val_t@std@@@Z"(i64 512, i64 32)
+// CHECK-MS: cleanuppad
+// CHECK-MS: call void @"\01??3@YAXPEAXW4align_val_t@std@@@Z"(i8* %[[ALLOC]], i64 32)
 void *a0() { return new A; }
 
+// FIXME: Why don't we call the sized array deallocation overload in this case?
+// The size is known.
+//
 // CHECK-LABEL: define {{.*}} @_Z2a1l(
 // CHECK: %[[ALLOC:.*]] = call i8* @_ZnamSt11align_val_t(i64 %{{.*}}, i64 32)
 // No array cookie.
 // CHECK-NOT: store
 // CHECK: invoke void @_ZN1AC1Ev(
 // CHECK: call void @_ZdaPvSt11align_val_t(i8* %[[ALLOC]], i64 32)
+// CHECK-MS-LABEL: define {{.*}} @"\01?a1@@YAPEAXJ@Z"(
+// CHECK-MS: %[[ALLOC:.*]] = call i8* @"\01??_U@YAPEAX_KW4align_val_t@std@@@Z"(i64 %{{.*}}, i64 32)
+// No array cookie.
+// CHECK-MS-NOT: store
+// CHECK-MS: invoke %struct.A* @"\01??0A@@QEAA@XZ"(
+// CHECK-MS: cleanuppad
+// CHECK-MS: call void @"\01??_V@YAXPEAXW4align_val_t@std@@@Z"(i8* %[[ALLOC]], i64 32)
 void *a1(long n) { return new A[n]; }
 
 // CHECK-LABEL: define {{.*}} @_Z2a2P1A(
Index: cfe/trunk/test/Preprocessor/init.c
===================================================================
--- cfe/trunk/test/Preprocessor/init.c
+++ cfe/trunk/test/Preprocessor/init.c
@@ -9890,11 +9890,11 @@
 
 
 // RUN: %clang_cc1 -E -dM -ffreestanding \
-// RUN:    -triple i686-windows-msvc -fms-compatibility < /dev/null \
+// RUN:    -triple i686-windows-msvc -fms-compatibility -x c++ < /dev/null \
 // RUN:  | FileCheck -match-full-lines -check-prefix MSVC-X32 %s
 
 // RUN: %clang_cc1 -E -dM -ffreestanding \
-// RUN:    -triple x86_64-windows-msvc -fms-compatibility < /dev/null \
+// RUN:    -triple x86_64-windows-msvc -fms-compatibility -x c++ < /dev/null \
 // RUN:  | FileCheck -match-full-lines -check-prefix MSVC-X64 %s
 
 // MSVC-X32:#define __CLANG_ATOMIC_BOOL_LOCK_FREE 2
@@ -9908,6 +9908,7 @@
 // MSVC-X32-NEXT:#define __CLANG_ATOMIC_SHORT_LOCK_FREE 2
 // MSVC-X32-NEXT:#define __CLANG_ATOMIC_WCHAR_T_LOCK_FREE 2
 // MSVC-X32-NOT:#define __GCC_ATOMIC{{.*}}
+// MSVC-X32:#define __STDCPP_DEFAULT_NEW_ALIGNMENT__ 8U
 
 // MSVC-X64:#define __CLANG_ATOMIC_BOOL_LOCK_FREE 2
 // MSVC-X64-NEXT:#define __CLANG_ATOMIC_CHAR16_T_LOCK_FREE 2
@@ -9919,7 +9920,8 @@
 // MSVC-X64-NEXT:#define __CLANG_ATOMIC_POINTER_LOCK_FREE 2
 // MSVC-X64-NEXT:#define __CLANG_ATOMIC_SHORT_LOCK_FREE 2
 // MSVC-X64-NEXT:#define __CLANG_ATOMIC_WCHAR_T_LOCK_FREE 2
-// MSVC-X86-NOT:#define __GCC_ATOMIC{{.*}}
+// MSVC-X64-NOT:#define __GCC_ATOMIC{{.*}}
+// MSVC-X64:#define __STDCPP_DEFAULT_NEW_ALIGNMENT__ 16ULL
 
 // RUN: %clang_cc1 -E -dM -ffreestanding                \
 // RUN:   -triple=aarch64-apple-ios9 < /dev/null        \