Index: lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
+++ lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
@@ -1513,6 +1513,9 @@
   SDValue AmtLack = DAG.getNode(ISD::SUB, dl, ShTy, NVBitsNode, Amt);
   SDValue isShort = DAG.getSetCC(dl, getSetCCResultType(ShTy),
                                  Amt, NVBitsNode, ISD::SETULT);
+  SDValue isZero = DAG.getSetCC(dl, getSetCCResultType(ShTy),
+                                Amt, DAG.getConstant(0, ShTy),
+                                ISD::SETEQ);
 
   SDValue LoS, HiS, LoL, HiL;
   switch (N->getOpcode()) {
@@ -1522,8 +1525,6 @@
     LoS = DAG.getNode(ISD::SHL, dl, NVT, InL, Amt);
     HiS = DAG.getNode(ISD::OR, dl, NVT,
                       DAG.getNode(ISD::SHL, dl, NVT, InH, Amt),
-    // FIXME: If Amt is zero, the following shift generates an undefined result
-    // on some architectures.
                       DAG.getNode(ISD::SRL, dl, NVT, InL, AmtLack));
 
     // Long: ShAmt >= NVTBits
@@ -1531,7 +1532,8 @@
     HiL = DAG.getNode(ISD::SHL, dl, NVT, InL, AmtExcess); // Hi from Lo part.
 
     Lo = DAG.getSelect(dl, NVT, isShort, LoS, LoL);
-    Hi = DAG.getSelect(dl, NVT, isShort, HiS, HiL);
+    Hi = DAG.getSelect(dl, NVT, isZero, InH,
+                       DAG.getSelect(dl, NVT, isShort, HiS, HiL));
     return true;
   case ISD::SRL:
     // Short: ShAmt < NVTBits
@@ -1546,7 +1548,8 @@
     HiL = DAG.getConstant(0, NVT);                        // Hi part is zero.
     LoL = DAG.getNode(ISD::SRL, dl, NVT, InH, AmtExcess); // Lo from Hi part.
 
-    Lo = DAG.getSelect(dl, NVT, isShort, LoS, LoL);
+    Lo = DAG.getSelect(dl, NVT, isZero, InL,
+                       DAG.getSelect(dl, NVT, isShort, LoS, LoL));
     Hi = DAG.getSelect(dl, NVT, isShort, HiS, HiL);
     return true;
   case ISD::SRA:
@@ -1554,8 +1557,6 @@
     HiS = DAG.getNode(ISD::SRA, dl, NVT, InH, Amt);
     LoS = DAG.getNode(ISD::OR, dl, NVT,
                       DAG.getNode(ISD::SRL, dl, NVT, InL, Amt),
-    // FIXME: If Amt is zero, the following shift generates an undefined result
-    // on some architectures.
                       DAG.getNode(ISD::SHL, dl, NVT, InH, AmtLack));
 
     // Long: ShAmt >= NVTBits
@@ -1563,7 +1564,8 @@
                       DAG.getConstant(NVTBits-1, ShTy));
     LoL = DAG.getNode(ISD::SRA, dl, NVT, InH, AmtExcess); // Lo from Hi part.
 
-    Lo = DAG.getSelect(dl, NVT, isShort, LoS, LoL);
+    Lo = DAG.getSelect(dl, NVT, isZero, InL,
+                       DAG.getSelect(dl, NVT, isShort, LoS, LoL));
     Hi = DAG.getSelect(dl, NVT, isShort, HiS, HiL);
     return true;
   }