Index: llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -1436,7 +1436,7 @@
   Type *ArgType = Op->getType();
   Value *F =
       Intrinsic::getDeclaration(Callee->getParent(), Intrinsic::cttz, ArgType);
-  Value *V = B.CreateCall(F, {Op, B.getFalse()}, "cttz");
+  Value *V = B.CreateCall(F, {Op, B.getTrue()}, "cttz");
   V = B.CreateAdd(V, ConstantInt::get(V->getType(), 1));
   V = B.CreateIntCast(V, B.getInt32Ty(), false);
 
Index: llvm/trunk/test/Transforms/InstCombine/ffs-1.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/ffs-1.ll
+++ llvm/trunk/test/Transforms/InstCombine/ffs-1.ll
@@ -102,7 +102,7 @@
 define i32 @test_simplify13(i32 %x) {
 ; CHECK-LABEL: @test_simplify13(
   %ret = call i32 @ffs(i32 %x)
-; CHECK-NEXT: [[CTTZ:%[a-z0-9]+]] = call i32 @llvm.cttz.i32(i32 %x, i1 false)
+; CHECK-NEXT: [[CTTZ:%[a-z0-9]+]] = call i32 @llvm.cttz.i32(i32 %x, i1 true)
 ; CHECK-NEXT: [[INC:%[a-z0-9]+]] = add nuw nsw i32 [[CTTZ]], 1
 ; CHECK-NEXT: [[CMP:%[a-z0-9]+]] = icmp ne i32 %x, 0
 ; CHECK-NEXT: [[RET:%[a-z0-9]+]] = select i1 [[CMP]], i32 [[INC]], i32 0
@@ -113,7 +113,7 @@
 define i32 @test_simplify14(i32 %x) {
 ; CHECK-LINUX-LABEL: @test_simplify14(
   %ret = call i32 @ffsl(i32 %x)
-; CHECK-LINUX-NEXT: [[CTTZ:%[a-z0-9]+]] = call i32 @llvm.cttz.i32(i32 %x, i1 false)
+; CHECK-LINUX-NEXT: [[CTTZ:%[a-z0-9]+]] = call i32 @llvm.cttz.i32(i32 %x, i1 true)
 ; CHECK-LINUX-NEXT: [[INC:%[a-z0-9]+]] = add nuw nsw i32 [[CTTZ]], 1
 ; CHECK-LINUX-NEXT: [[CMP:%[a-z0-9]+]] = icmp ne i32 %x, 0
 ; CHECK-LINUX-NEXT: [[RET:%[a-z0-9]+]] = select i1 [[CMP]], i32 [[INC]], i32 0
@@ -124,7 +124,7 @@
 define i32 @test_simplify15(i64 %x) {
 ; CHECK-LINUX-LABEL: @test_simplify15(
   %ret = call i32 @ffsll(i64 %x)
-; CHECK-LINUX-NEXT: [[CTTZ:%[a-z0-9]+]] = call i64 @llvm.cttz.i64(i64 %x, i1 false)
+; CHECK-LINUX-NEXT: [[CTTZ:%[a-z0-9]+]] = call i64 @llvm.cttz.i64(i64 %x, i1 true)
 ; CHECK-LINUX-NEXT: [[INC:%[a-z0-9]+]] = add nuw nsw i64 [[CTTZ]], 1
 ; CHECK-LINUX-NEXT: [[TRUNC:%[a-z0-9]+]] = trunc i64 [[INC]] to i32
 ; CHECK-LINUX-NEXT: [[CMP:%[a-z0-9]+]] = icmp ne i64 %x, 0