diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index d817c484334..ad9d85346a9 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -2322,7 +2322,8 @@ SDValue DAGCombiner::visitOR(SDNode *N) {
   }
 
   // fold (or x, undef) -> -1
-  if (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF) {
+  if (!LegalOperations &&
+      (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF)) {
     EVT EltVT = VT.isVector() ? VT.getVectorElementType() : VT;
     return DAG.getConstant(APInt::getAllOnesValue(EltVT.getSizeInBits()), VT);
   }
diff --git a/test/CodeGen/ARM/2010-06-28-DAGCombineUndef.ll b/test/CodeGen/ARM/2010-06-28-DAGCombineUndef.ll
new file mode 100644
index 00000000000..ad2810b5bb9
--- /dev/null
+++ b/test/CodeGen/ARM/2010-06-28-DAGCombineUndef.ll
@@ -0,0 +1,10 @@
+; RUN: llc < %s -march=arm -mattr=+neon
+
+define void @main() nounwind {
+entry:
+  store <2 x i64> undef, <2 x i64>* undef, align 16
+  %0 = load <16 x i8>* undef, align 16            ; <<16 x i8>> [#uses=1]
+  %1 = or <16 x i8> zeroinitializer, %0           ; <<16 x i8>> [#uses=1]
+  store <16 x i8> %1, <16 x i8>* undef, align 16
+  ret void
+}