diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index b7f6853f74c..7adfecb2220 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1547,7 +1547,9 @@ SDOperand DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
   if (N0.getOpcode() == ISD::SEXTLOAD && VT == N0.getValueType())
     return N0;
   // fold (sext (truncate x)) -> (sextinreg x) iff x size == sext size.
-  if (N0.getOpcode() == ISD::TRUNCATE && N0.getOperand(0).getValueType() == VT)
+  if (N0.getOpcode() == ISD::TRUNCATE && N0.getOperand(0).getValueType() == VT&&
+      (!AfterLegalize || 
+       TLI.isOperationLegal(ISD::SIGN_EXTEND_INREG, N0.getValueType())))
     return DAG.getNode(ISD::SIGN_EXTEND_INREG, VT, N0.getOperand(0),
                        DAG.getValueType(N0.getValueType()));
   // fold (sext (load x)) -> (sextload x)