Index: clang/lib/AST/MicrosoftMangle.cpp
===================================================================
--- clang/lib/AST/MicrosoftMangle.cpp
+++ clang/lib/AST/MicrosoftMangle.cpp
@@ -337,6 +337,8 @@
   void mangleArgumentType(QualType T, SourceRange Range);
   void manglePassObjectSizeArg(const PassObjectSizeAttr *POSA);
 
+  bool isArtificialTagType(QualType T) const;
+
   // Declare manglers for every type class.
 #define ABSTRACT_TYPE(CLASS, PARENT)
 #define NON_CANONICAL_TYPE(CLASS, PARENT)
@@ -1751,7 +1753,7 @@
     Quals.removeUnaligned();
     if (Quals.hasObjCLifetime())
       Quals = Quals.withoutObjCLifetime();
-    if ((!IsPointer && Quals) || isa<TagType>(T)) {
+    if ((!IsPointer && Quals) || isa<TagType>(T) || isArtificialTagType(T)) {
       Out << '?';
       mangleQualifiers(Quals, false);
     }
@@ -2280,6 +2282,8 @@
   mangleTagTypeKind(TD->getTagKind());
   mangleName(TD);
 }
+
+// If you add a call to this, consider udpating isArtificialTagType() too.
 void MicrosoftCXXNameMangler::mangleArtificalTagType(
     TagTypeKind TK, StringRef UnqualifiedName, ArrayRef<StringRef> NestedNames) {
   // <name> ::= <unscoped-name> {[<named-scope>]+ | [<nested-name>]}? @
@@ -2468,6 +2472,26 @@
   mangleArtificalTagType(TTK_Struct, TemplateMangling, {"__clang"});
 }
 
+// Returns true for types that mangleArtificalTagType() gets called for with
+// TTK_Union, TTK_Struct, TTK_Class and where compatibility with MSVC's
+// mangling matters.
+// (It doesn't matter for Objective-C types and the like that cl.exe doesn't
+// support.)
+bool MicrosoftCXXNameMangler::isArtificialTagType(QualType T) const {
+  const Type *ty = T.getTypePtr();
+  switch (ty->getTypeClass()) {
+  default:
+    return false;
+
+  case Type::Vector: {
+    // For ABI compatibility only __m64, __m128(id), and __m256(id) matter,
+    // but since mangleType(VectorType*) always calls mangleArtificalTagType()
+    // just always return true (the other vector types are clang-only).
+    return true;
+  }
+  }
+}
+
 void MicrosoftCXXNameMangler::mangleType(const VectorType *T, Qualifiers Quals,
                                          SourceRange Range) {
   const BuiltinType *ET = T->getElementType()->getAs<BuiltinType>();
Index: clang/test/CodeGenCXX/mangle-ms-vector-types.cpp
===================================================================
--- clang/test/CodeGenCXX/mangle-ms-vector-types.cpp
+++ clang/test/CodeGenCXX/mangle-ms-vector-types.cpp
@@ -1,30 +1,91 @@
-// RUN: %clang_cc1 -fms-extensions -ffreestanding -target-feature +avx -emit-llvm %s -o - -triple=i686-pc-win32 | FileCheck %s
+// RUN: %clang_cc1 -fms-extensions -fcxx-exceptions -ffreestanding -target-feature +avx -emit-llvm %s -o - -triple=i686-pc-win32 | FileCheck %s
 
 #include <xmmintrin.h>
 #include <emmintrin.h>
 #include <immintrin.h>
 
+void thow(int i) {
+  switch (i) {
+    case 0: throw __m64();
+    // CHECK: ??_R0?AT__m64@@@8
+    // CHECK: _CT??_R0?AT__m64@@@88
+    // CHECK: _CTA1?AT__m64@@
+    // CHECK: _TI1?AT__m64@@
+    case 1: throw __m128();
+    // CHECK: ??_R0?AT__m128@@@8
+    // CHECK: _CT??_R0?AT__m128@@@816
+    // CHECK: _CTA1?AT__m128@@
+    // CHECK: _TI1?AT__m128@@
+    case 2: throw __m128d();
+    // CHECK: ??_R0?AU__m128d@@@8
+    // CHECK: _CT??_R0?AU__m128d@@@816
+    // CHECK: _CTA1?AU__m128d@@
+    // CHECK: _TI1?AU__m128d@@
+    case 3: throw __m128i();
+    // CHECK: ??_R0?AT__m128i@@@8
+    // CHECK: _CT??_R0?AT__m128i@@@816
+    // CHECK: _CTA1?AT__m128i@@
+    // CHECK: _TI1?AT__m128i@@
+    case 4: throw __m256();
+    // CHECK: ??_R0?AT__m256@@@8
+    // CHECK: _CT??_R0?AT__m256@@@832
+    // CHECK: _CTA1?AT__m256@@
+    // CHECK: _TI1?AT__m256@@
+    case 5: throw __m256d();
+    // CHECK: ??_R0?AU__m256d@@@8
+    // CHECK: _CT??_R0?AU__m256d@@@832
+    // CHECK: _CTA1?AU__m256d@@
+    // CHECK: _TI1?AU__m256d@@
+    case 6: throw __m256i();
+    // CHECK: ??_R0?AT__m256@@@8
+    // CHECK: _CT??_R0?AT__m256@@@832
+    // CHECK: _CTA1?AT__m256@@
+    // CHECK: _TI1?AT__m256@@
+  }
+}
+
 void foo64(__m64) {}
 // CHECK: define dso_local void @"?foo64@@YAXT__m64@@@Z"
 
+__m64 rfoo64() { return __m64(); }
+// CHECK: define dso_local <1 x i64> @"?rfoo64@@YA?AT__m64@@XZ"
+
 void foo128(__m128) {}
 // CHECK: define dso_local void @"?foo128@@YAXT__m128@@@Z"
 
+const __m128 rfoo128() { return __m128(); }
+// CHECK: define dso_local <4 x float> @"?rfoo128@@YA?BT__m128@@XZ"
+
 void foo128d(__m128d) {}
 // CHECK: define dso_local void @"?foo128d@@YAXU__m128d@@@Z"
 
+volatile __m128d rfoo128d() { return __m128d(); }
+// CHECK: define dso_local <2 x double> @"?rfoo128d@@YA?CU__m128d@@XZ"
+
 void foo128i(__m128i) {}
 // CHECK: define dso_local void @"?foo128i@@YAXT__m128i@@@Z"
 
+const volatile __m128i rfoo128i() { return __m128i(); }
+// CHECK: define dso_local <2 x i64> @"?rfoo128i@@YA?DT__m128i@@XZ"
+
 void foo256(__m256) {}
 // CHECK: define dso_local void @"?foo256@@YAXT__m256@@@Z"
 
+__m256 rfoo256() { return __m256(); }
+// CHECK: define dso_local <8 x float> @"?rfoo256@@YA?AT__m256@@XZ"
+
 void foo256d(__m256d) {}
 // CHECK: define dso_local void @"?foo256d@@YAXU__m256d@@@Z"
 
+__m256d rfoo256d() { return __m256d(); }
+// CHECK: define dso_local <4 x double> @"?rfoo256d@@YA?AU__m256d@@XZ"
+
 void foo256i(__m256i) {}
 // CHECK: define dso_local void @"?foo256i@@YAXT__m256i@@@Z"
 
+__m256i rfoo256i() { return __m256i(); }
+// CHECK: define dso_local <4 x i64> @"?rfoo256i@@YA?AT__m256i@@XZ"
+
 // We have a custom mangling for vector types not standardized by Intel.
 void foov8hi(__v8hi) {}
 // CHECK: define dso_local void @"?foov8hi@@YAXT?$__vector@F$07@__clang@@@Z"