diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index af82feb3d72..44c95b5a6ff 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -7654,9 +7654,12 @@ SDValue X86TargetLowering::LowerXALUO(SDValue Op, SelectionDAG &DAG) const {
 SDValue X86TargetLowering::LowerMEMBARRIER(SDValue Op, SelectionDAG &DAG) const{
   DebugLoc dl = Op.getDebugLoc();
   
-  if (!Subtarget->hasSSE2())
+  if (!Subtarget->hasSSE2()) {
+    SDValue Zero = DAG.getConstant(0,
+                                   Subtarget->is64Bit() ? MVT::i64 : MVT::i32);
     return DAG.getNode(X86ISD::MEMBARRIER, dl, MVT::Other, Op.getOperand(0),
-                       DAG.getConstant(0, MVT::i32));
+                       Zero);
+  }
   
   unsigned isDev = cast<ConstantSDNode>(Op.getOperand(5))->getZExtValue();
   if(!isDev)
diff --git a/lib/Target/X86/X86Instr64bit.td b/lib/Target/X86/X86Instr64bit.td
index 9c7c80f2372..04b75f9f8bc 100644
--- a/lib/Target/X86/X86Instr64bit.td
+++ b/lib/Target/X86/X86Instr64bit.td
@@ -1619,6 +1619,13 @@ def MOV64FSrm : RI<0x8B, MRMSrcMem, (outs GR64:$dst), (ins i64mem:$src),
 // Atomic Instructions
 //===----------------------------------------------------------------------===//
 
+// TODO: Get this to fold the constant into the instruction.           
+let Defs = [ESP] in
+def Int_MemBarrierNoSSE64  : RI<0x09, MRM1r, (outs), (ins GR64:$zero),
+                           "lock\n\t"
+                           "or{q}\t{$zero, (%rsp)|(%rsp), $zero}",
+                           [(X86MemBarrierNoSSE GR64:$zero)]>, LOCK;
+
 let Defs = [RAX, EFLAGS], Uses = [RAX] in {
 def LCMPXCHG64 : RI<0xB1, MRMDestMem, (outs), (ins i64mem:$ptr, GR64:$swap),
                "lock\n\t"
diff --git a/lib/Target/X86/X86InstrInfo.td b/lib/Target/X86/X86InstrInfo.td
index 367e29c77a6..5fc1bb7be1b 100644
--- a/lib/Target/X86/X86InstrInfo.td
+++ b/lib/Target/X86/X86InstrInfo.td
@@ -3934,8 +3934,8 @@ def Int_MemBarrier : I<0, Pseudo, (outs), (ins),
                      [(X86MemBarrier)]>, Requires<[HasSSE2]>;
 
 // TODO: Get this to fold the constant into the instruction.           
-let Uses = [ESP] in
-def Int_MemBarrierNoSSE  : I<0x0B, Pseudo, (outs), (ins GR32:$zero),
+let Defs = [ESP] in
+def Int_MemBarrierNoSSE  : I<0x09, MRM1r, (outs), (ins GR32:$zero),
                            "lock\n\t"
                            "or{l}\t{$zero, (%esp)|(%esp), $zero}",
                            [(X86MemBarrierNoSSE GR32:$zero)]>, LOCK;