diff --git a/llvm/lib/Target/X86/X86AsmPrinter.cpp b/llvm/lib/Target/X86/X86AsmPrinter.cpp
--- a/llvm/lib/Target/X86/X86AsmPrinter.cpp
+++ b/llvm/lib/Target/X86/X86AsmPrinter.cpp
@@ -407,7 +407,7 @@
 static bool printAsmMRegister(X86AsmPrinter &P, const MachineOperand &MO,
                               char Mode, raw_ostream &O) {
   Register Reg = MO.getReg();
-  bool EmitPercent = true;
+  bool EmitPercent = MO.getParent()->getInlineAsmDialect() == InlineAsm::AD_ATT;
 
   if (!X86::GR8RegClass.contains(Reg) &&
       !X86::GR16RegClass.contains(Reg) &&
@@ -446,6 +446,41 @@
   return false;
 }
 
+static bool printAsmVRegister(X86AsmPrinter &P, const MachineOperand &MO,
+                              char Mode, raw_ostream &O) {
+  unsigned Reg = MO.getReg();
+  bool EmitPercent = MO.getParent()->getInlineAsmDialect() == InlineAsm::AD_ATT;
+
+  unsigned Index;
+  if (X86::VR128XRegClass.contains(Reg))
+    Index = Reg - X86::XMM0;
+  else if (X86::VR256XRegClass.contains(Reg))
+    Index = Reg - X86::YMM0;
+  else if (X86::VR512RegClass.contains(Reg))
+    Index = Reg - X86::ZMM0;
+  else
+    return true;
+
+  switch (Mode) {
+  default: return true;  // Unknown mode.
+  case 'x': // Print V4SFmode register
+    Reg = X86::XMM0 + Index;
+    break;
+  case 't': // Print V8SFmode register
+    Reg = X86::YMM0 + Index;
+    break;
+  case 'g': // Print V16SFmode register
+    Reg = X86::ZMM0 + Index;
+    break;
+  }
+
+  if (EmitPercent)
+    O << '%';
+
+  O << X86ATTInstPrinter::getRegisterName(Reg);
+  return false;
+}
+
 /// PrintAsmOperand - Print out an operand for an inline asm expression.
 ///
 bool X86AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
@@ -520,6 +555,14 @@
       PrintOperand(MI, OpNo, O);
       return false;
 
+    case 'x': // Print V4SFmode register
+    case 't': // Print V8SFmode register
+    case 'g': // Print V16SFmode register
+      if (MO.isReg())
+        return printAsmVRegister(*this, MO, ExtraCode[0], O);
+      PrintOperand(MI, OpNo, O);
+      return false;
+
     case 'P': // This is the operand of a call, treat specially.
       PrintPCRelImm(MI, OpNo, O);
       return false;
diff --git a/llvm/test/CodeGen/X86/asm-modifier2.ll b/llvm/test/CodeGen/X86/asm-modifier2.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/asm-modifier2.ll
@@ -0,0 +1,53 @@
+; RUN: llc < %s | FileCheck %s
+
+define void @test1() {
+; CHECK-LABEL: test1:
+; CHECK: vmovaps %xmm0, %xmm0
+; CHECK: vmovaps %ymm0, %ymm0
+; CHECK: vmovaps %zmm0, %zmm0
+  tail call void asm sideeffect "vmovaps ${0:x}, ${0:x}", "{xmm0},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  tail call void asm sideeffect "vmovaps ${0:t}, ${0:t}", "{xmm0},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  tail call void asm sideeffect "vmovaps ${0:g}, ${0:g}", "{xmm0},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  ret void
+}
+
+define void @test2() {
+; CHECK-LABEL: test2:
+; CHECK: vmovaps %xmm0, %xmm0
+; CHECK: vmovaps %ymm0, %ymm0
+; CHECK: vmovaps %zmm0, %zmm0
+  tail call void asm sideeffect inteldialect "vmovaps ${0:x}, ${0:x}", "{xmm0},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  tail call void asm sideeffect inteldialect "vmovaps ${0:t}, ${0:t}", "{xmm0},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  tail call void asm sideeffect inteldialect "vmovaps ${0:g}, ${0:g}", "{xmm0},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  ret void
+}
+
+define void @test3() {
+; CHECK-LABEL: test3:
+; CHECK: movb %al, %al
+; CHECK: movb %ah, %ah
+; CHECK: movw %ax, %ax
+; CHECK: movl %eax, %eax
+; CHECK: movq %rax, %rax
+  tail call void asm sideeffect "mov ${0:b}, ${0:b}", "{eax},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  tail call void asm sideeffect "mov ${0:h}, ${0:h}", "{eax},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  tail call void asm sideeffect "mov ${0:w}, ${0:w}", "{eax},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  tail call void asm sideeffect "mov ${0:k}, ${0:k}", "{eax},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  tail call void asm sideeffect "mov ${0:q}, ${0:q}", "{eax},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  ret void
+}
+
+define void @test4() {
+; CHECK-LABEL: test4:
+; CHECK: movb %al, %al
+; CHECK: movb %ah, %ah
+; CHECK: movw %ax, %ax
+; CHECK: movl %eax, %eax
+; CHECK: movq %rax, %rax
+  tail call void asm sideeffect inteldialect "mov ${0:b}, ${0:b}", "{eax},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  tail call void asm sideeffect inteldialect "mov ${0:h}, ${0:h}", "{eax},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  tail call void asm sideeffect inteldialect "mov ${0:w}, ${0:w}", "{eax},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  tail call void asm sideeffect inteldialect "mov ${0:k}, ${0:k}", "{eax},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  tail call void asm sideeffect inteldialect "mov ${0:q}, ${0:q}", "{eax},~{dirflag},~{fpsr},~{flags}"(i32 0)
+  ret void
+}