Index: llvm/trunk/lib/Analysis/TargetLibraryInfo.cpp
===================================================================
--- llvm/trunk/lib/Analysis/TargetLibraryInfo.cpp
+++ llvm/trunk/lib/Analysis/TargetLibraryInfo.cpp
@@ -608,7 +608,7 @@
     return (NumParams == 3 && FTy.getReturnType()->isPointerTy() &&
             FTy.getParamType(0) == FTy.getReturnType() &&
             FTy.getParamType(1) == FTy.getReturnType() &&
-            FTy.getParamType(2)->isIntegerTy());
+            IsSizeTTy(FTy.getParamType(2)));
 
   case LibFunc_strcpy_chk:
   case LibFunc_stpcpy_chk:
@@ -633,7 +633,7 @@
     return (NumParams == 3 && FTy.getReturnType() == FTy.getParamType(0) &&
             FTy.getParamType(0) == FTy.getParamType(1) &&
             FTy.getParamType(0) == PCharTy &&
-            FTy.getParamType(2)->isIntegerTy());
+            IsSizeTTy(FTy.getParamType(2)));
 
   case LibFunc_strxfrm:
     return (NumParams == 3 && FTy.getParamType(0)->isPointerTy() &&
@@ -648,7 +648,7 @@
     return (NumParams == 3 && FTy.getReturnType()->isIntegerTy(32) &&
             FTy.getParamType(0)->isPointerTy() &&
             FTy.getParamType(0) == FTy.getParamType(1) &&
-            FTy.getParamType(2)->isIntegerTy());
+            IsSizeTTy(FTy.getParamType(2)));
 
   case LibFunc_strspn:
   case LibFunc_strcspn:
Index: llvm/trunk/test/Transforms/InstCombine/strncmp-wrong-datalayout.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/strncmp-wrong-datalayout.ll
+++ llvm/trunk/test/Transforms/InstCombine/strncmp-wrong-datalayout.ll
@@ -0,0 +1,16 @@
+; Test that the strncpy simplification doesn't crash if datalayout specifies
+; 64 bit pointers while length is a 32 bit argument
+;
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64"
+
+declare i32 @strncmp(i8*, i8*, i32)
+
+define i32 @test6(i8* %str1, i8* %str2) {
+; CHECK-LABEL: @test6(
+; CHECK: call i32 @strncmp(i8* %str1, i8* %str2, i32 1)
+
+  %temp1 = call i32 @strncmp(i8* %str1, i8* %str2, i32 1)
+  ret i32 %temp1
+}