diff --git a/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index 03be8ef6fb7..c6d60d6f008 100644
--- a/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -1250,6 +1250,16 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
 
     if (SimplifyDemandedInstructionBits(I))
       return &I;
+
+    // Fold (sub 0, (zext bool to B)) --> (sext bool to B)
+    if (C->isZero() && match(Op1, m_ZExt(m_Value(X))))
+      if (X->getType()->isIntegerTy(1))
+        return CastInst::CreateSExtOrBitCast(X, Op1->getType());
+
+    // Fold (sub 0, (sext bool to B)) --> (zext bool to B)
+    if (C->isZero() && match(Op1, m_SExt(m_Value(X))))
+      if (X->getType()->isIntegerTy(1))
+        return CastInst::CreateZExtOrBitCast(X, Op1->getType());
   }
 
 
diff --git a/test/Transforms/InstCombine/mul.ll b/test/Transforms/InstCombine/mul.ll
index bbc70fe3334..34ce088e293 100644
--- a/test/Transforms/InstCombine/mul.ll
+++ b/test/Transforms/InstCombine/mul.ll
@@ -138,8 +138,7 @@ define i32 @test16(i32 %b, i1 %c) {
         ; e = b & (a >> 31)
         %e = mul i32 %d, %b             ; <i32> [#uses=1]
         ret i32 %e
-; CHECK: [[TEST16:%.*]] = zext i1 %c to i32
-; CHECK-NEXT: %1 = sub i32 0, [[TEST16]]
+; CHECK: [[TEST16:%.*]] = sext i1 %c to i32
 ; CHECK-NEXT: %e = and i32 %1, %b
 ; CHECK-NEXT: ret i32 %e
 }
diff --git a/test/Transforms/InstCombine/sext.ll b/test/Transforms/InstCombine/sext.ll
index f1987973f46..968f37c9c12 100644
--- a/test/Transforms/InstCombine/sext.ll
+++ b/test/Transforms/InstCombine/sext.ll
@@ -184,3 +184,12 @@ define i32 @test16(i16 %x) nounwind {
 ; CHECK-NEXT: %ext = sext i16 %sext to i32
 ; CHECK-NEXT: ret i32 %ext
 }
+
+define i32 @test17(i1 %x) nounwind {
+  %c1 = sext i1 %x to i32
+  %c2 = sub i32 0, %c1
+  ret i32 %c2
+; CHECK: @test17
+; CHECK-NEXT: [[TEST17:%.*]] = zext i1 %x to i32
+; CHECK-NEXT: ret i32 [[TEST17]]
+}
diff --git a/test/Transforms/InstCombine/zext-bool-add-sub.ll b/test/Transforms/InstCombine/zext-bool-add-sub.ll
index 78bcedbbc2e..b5310575502 100644
--- a/test/Transforms/InstCombine/zext-bool-add-sub.ll
+++ b/test/Transforms/InstCombine/zext-bool-add-sub.ll
@@ -4,9 +4,9 @@
 define i32 @a(i1 zeroext %x, i1 zeroext %y) {
 entry:
 ; CHECK: @a
-; CHECK: [[TMP1:%.*]] = zext i1 %y to i32
+; CHECK: [[TMP1:%.*]] = sext i1 %y to i32
 ; CHECK: [[TMP2:%.*]] = select i1 %x, i32 2, i32 1
-; CHECK-NEXT: sub i32 [[TMP2]], [[TMP1]]
+; CHECK-NEXT: add i32 [[TMP2]], [[TMP1]]
   %conv = zext i1 %x to i32
   %conv3 = zext i1 %y to i32
   %conv3.neg = sub i32 0, %conv3