diff --git a/lib/Target/X86/X86InstrMMX.td b/lib/Target/X86/X86InstrMMX.td
index 1a2a3bffb24..e9a8f582dd0 100644
--- a/lib/Target/X86/X86InstrMMX.td
+++ b/lib/Target/X86/X86InstrMMX.td
@@ -164,11 +164,14 @@ def MMX_MOVD64to64rr : MMXRI<0x6E, MRMSrcReg, (outs VR64:$dst), (ins GR64:$src),
                              []>;
 
 let neverHasSideEffects = 1 in {
+// These are 64 bit moves, but since the OS X assembler doesn't
+// recognize a register-register movq, we write them as
+// movd.
 def MMX_MOVD64from64rr : MMXRI<0x7E, MRMDestReg,
                                (outs GR64:$dst), (ins VR64:$src),
-                               "movq\t{$src, $dst|$dst, $src}", []>;
+                               "movd\t{$src, $dst|$dst, $src}", []>;
 def MMX_MOVD64rrv164 : MMXI<0x6E, MRMSrcReg, (outs VR64:$dst), (ins GR64:$src),
-                            "movq\t{$src, $dst|$dst, $src}",
+                            "movd\t{$src, $dst|$dst, $src}",
                             [(set VR64:$dst, (v1i64 (scalar_to_vector GR64:$src)))]>;
 }
 
diff --git a/test/CodeGen/X86/mmx-bitcast-to-i64.ll b/test/CodeGen/X86/mmx-bitcast-to-i64.ll
index 04c4dd05660..c6bb48927b6 100644
--- a/test/CodeGen/X86/mmx-bitcast-to-i64.ll
+++ b/test/CodeGen/X86/mmx-bitcast-to-i64.ll
@@ -1,4 +1,4 @@
-; RUN: llvm-as < %s | llc -march=x86-64 | grep movq | count 8
+; RUN: llvm-as < %s | llc -march=x86-64 | grep movd | count 4
 
 define i64 @foo(<1 x i64>* %p) {
   %t = load <1 x i64>* %p