Index: lib/Basic/Targets.cpp
===================================================================
--- lib/Basic/Targets.cpp
+++ lib/Basic/Targets.cpp
@@ -2987,6 +2987,15 @@
     // In case the constraint is 'r' we need to return Expression
     case 'r':
       return Expression;
+    case 'Y':
+      switch (*++I)
+      {
+      default:
+        return "";
+      case '0': // First SSE register.
+      case 'z':
+        return "xmm0";
+      }
     default:
       // Default value if there is no constraint for the register
       return "";
@@ -4314,8 +4323,10 @@
     default:
       return false;
     case '0': // First SSE register.
-    case 't': // Any SSE register, when SSE2 is enabled.
-    case 'i': // Any SSE register, when SSE2 and inter-unit moves enabled.
+    case 'z': // First SSE register.
+    case '2': // Any SSE register, when SSE2 is enabled.
+    case 't': // Any SSE register, when SSE2 is enabled (GCC).
+    case 'i': // Any SSE register, when SSE2 and inter-unit moves enabled(GCC).
     case 'm': // Any MMX register, when inter-unit moves enabled.
     case 'k': // AVX512 arch mask registers: k1-k7.
       Info.setAllowsRegister();
@@ -4400,9 +4411,12 @@
       // 'Ym' is synonymous with 'y'.
     case 'k':
       return Size <= 64;
-    case 'i':
+    case 'z': // First SSE register xmm0. 
+    case '0':
+    case '2': // Any SSE register when SSE 2 is enabled (ICC).
+    case 'i': 
     case 't':
-      // 'Yi' and 'Yt' are synonymous with 'x' when SSE2 is enabled.
+      // 'Y2' 'Yi' and 'Yt' are synonymous with 'x' when SSE2 is enabled.
       if (SSELevel >= AVX512F)
         return Size <= 512U;
       else if (SSELevel >= AVX)
@@ -4438,6 +4452,11 @@
       // the return string.
       break;
     case 'k':
+    case 'm':
+    case 'i':
+    case '2':
+    case 'z':
+    case '0':
       // "^" hints llvm that this is a 2 letter constraint.
       // "Constraint++" is used to promote the string iterator 
       // to the next constraint.
Index: lib/CodeGen/TargetInfo.cpp
===================================================================
--- lib/CodeGen/TargetInfo.cpp
+++ lib/CodeGen/TargetInfo.cpp
@@ -845,7 +845,7 @@
 static llvm::Type* X86AdjustInlineAsmType(CodeGen::CodeGenFunction &CGF,
                                           StringRef Constraint,
                                           llvm::Type* Ty) {
-  if ((Constraint == "y" || Constraint == "&y") && Ty->isVectorTy()) {
+  if ((Constraint == "y" || Constraint == "&y" || Constraint =="^Ym") && Ty->isVectorTy()) {
     if (cast<llvm::VectorType>(Ty)->getBitWidth() != 64) {
       // Invalid MMX constraint
       return nullptr;
Index: test/CodeGen/x86-GCC-inline-asm-Y-constraints.c
===================================================================
--- test/CodeGen/x86-GCC-inline-asm-Y-constraints.c
+++ test/CodeGen/x86-GCC-inline-asm-Y-constraints.c
@@ -0,0 +1,57 @@
+// RUN: %clang_cc1 -ffreestanding  -triple=x86_64-apple-darwin -target-cpu skx %s -emit-llvm -o - | FileCheck %s
+#include <xmmintrin.h>
+// This test is complimented by the .ll test under llvm/test/MC/X86/. 
+// At this level we can only check if the constarints are passed correctly
+// from inline asm to llvm IR.
+
+// CHECK-LABEL: @f_Ym
+void f_Ym(__m64 m)
+  {
+  // CHECK: movq  $0, %mm1
+  // CHECK-SAME: "=^Ym,~{dirflag},~{fpsr},~{flags}"
+  __asm__ volatile ("movq %0, %%mm1\n\t"
+          :"=Ym" (m));
+}
+
+// CHECK-LABEL: f_Yi
+void f_Yi(__m128 x, __m128 y, __m128 z)
+  {
+  // CHECK: vpaddq
+  // CHECK-SAME: "=^Yi,^Yi,^Yi,~{dirflag},~{fpsr},~{flags}"
+  __asm__ volatile ("vpaddq %0, %1, %2\n\t"
+          :"=Yi" (x)
+          :"Yi" (y),"Yi"(z));
+}
+
+// CHECK-LABEL: f_Y2
+void f_Y2(__m128 x, __m128 y, __m128 z)
+    {
+  // CHECK: vpaddq
+  // CHECK-SAME: "=^Y2,^Y2,^Y2,~{dirflag},~{fpsr},~{flags}"
+  __asm__ volatile ("vpaddq %0, %1, %2\n\t"
+            :"=Y2" (x)
+            :"Y2" (y),"Y2"(z));
+}
+
+// CHECK-LABEL: f_Yz
+void f_Yz(__m128 x, __m128 y, __m128 z)
+  {
+  // CHECK: vpaddq
+  // CHECK-SAME: vpaddq
+  // CHECK-SAME: "=^Yi,=^Yz,^Yi,0,~{dirflag},~{fpsr},~{flags}"
+  __asm__ volatile ("vpaddq %0,%2,%1\n\t"
+	      "vpaddq %1,%0,%2\n\t"
+          :"+Yi"(z),"=Yz" (x)
+          :"Yi" (y) );
+}
+
+// CHECK-LABEL: f_Y0
+void f_Y0(__m128 x, __m128 y, __m128 z)
+  {
+  // CHECK: vpaddq
+  // CHECK-SAME: "=^Yi,=^Y0,^Yi,0,~{dirflag},~{fpsr},~{flags}"
+  __asm__ volatile ("vpaddq %0,%2,%1\n\t"
+          "vpaddq %1,%0,%2\n\t"
+          :"+Yi"(z),"=Y0" (x)
+          :"Yi" (y) );
+}
\ No newline at end of file