diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 1aca833c3c2f..667dca14a5a0 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -352,10 +352,13 @@ static void getCopyToParts(SelectionDAG &DAG, DebugLoc DL,
       assert(NumParts == 1 && "Do not know what to promote to!");
       Val = DAG.getNode(ISD::FP_EXTEND, DL, PartVT, Val);
     } else {
-      assert(PartVT.isInteger() && ValueVT.isInteger() &&
+      assert((PartVT.isInteger() || PartVT == MVT::x86mmx) &&
+             ValueVT.isInteger() &&
              "Unknown mismatch!");
       ValueVT = EVT::getIntegerVT(*DAG.getContext(), NumParts * PartBits);
       Val = DAG.getNode(ExtendKind, DL, ValueVT, Val);
+      if (PartVT == MVT::x86mmx)
+        Val = DAG.getNode(ISD::BITCAST, DL, PartVT, Val);
     }
   } else if (PartBits == ValueVT.getSizeInBits()) {
     // Different types of the same size.
@@ -363,10 +366,13 @@ static void getCopyToParts(SelectionDAG &DAG, DebugLoc DL,
     Val = DAG.getNode(ISD::BITCAST, DL, PartVT, Val);
   } else if (NumParts * PartBits < ValueVT.getSizeInBits()) {
     // If the parts cover less bits than value has, truncate the value.
-    assert(PartVT.isInteger() && ValueVT.isInteger() &&
+    assert((PartVT.isInteger() || PartVT == MVT::x86mmx) &&
+           ValueVT.isInteger() &&
            "Unknown mismatch!");
     ValueVT = EVT::getIntegerVT(*DAG.getContext(), NumParts * PartBits);
     Val = DAG.getNode(ISD::TRUNCATE, DL, ValueVT, Val);
+    if (PartVT == MVT::x86mmx)
+      Val = DAG.getNode(ISD::BITCAST, DL, PartVT, Val);
   }
 
   // The value may have changed - recompute ValueVT.
diff --git a/llvm/test/CodeGen/X86/2012-02-23-mmx-inlineasm.ll b/llvm/test/CodeGen/X86/2012-02-23-mmx-inlineasm.ll
new file mode 100644
index 000000000000..1d239d6667d0
--- /dev/null
+++ b/llvm/test/CodeGen/X86/2012-02-23-mmx-inlineasm.ll
@@ -0,0 +1,12 @@
+; RUN: llc -mcpu=i686 -mattr=+mmx < %s | FileCheck %s
+; <rdar://problem/10106006>
+
+define void @func() nounwind ssp {
+; CHECK:  psrlw %mm0, %mm1
+entry:
+  call void asm sideeffect "psrlw $0, %mm1", "y,~{dirflag},~{fpsr},~{flags}"(i32 8) nounwind
+  unreachable
+
+bb367:                                            ; preds = %entry                                                                                                                 
+  ret void
+}