Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -10002,8 +10002,11 @@
     if (ISD::isNON_TRUNCStore(Chain.getNode())) {
       StoreSDNode *PrevST = cast<StoreSDNode>(Chain);
       if (PrevST->getBasePtr() == Ptr &&
-          PrevST->getValue().getValueType() == N->getValueType(0))
-      return CombineTo(N, Chain.getOperand(1), Chain);
+          PrevST->getValue().getValueType() == N->getValueType(0)) {
+        if (OptLevel != CodeGenOpt::None ||
+            !isa<ConstantSDNode>(Chain.getOperand(1)))
+          return CombineTo(N, Chain.getOperand(1), Chain);
+      }
     }
   }