diff --git a/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
index 3cab795..2ae3286 100644
--- a/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ b/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -270,6 +270,7 @@
     return NULL;
 
   if (BitWidth > LOI->KnownZero.getBitWidth()) {
+    LOI->NumSignBits = 1;
     LOI->KnownZero = LOI->KnownZero.zextOrTrunc(BitWidth);
     LOI->KnownOne = LOI->KnownOne.zextOrTrunc(BitWidth);
   }