diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 7509e91bdc8..07a18fe4de4 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -249,7 +249,10 @@ void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
   }
   case Instruction::BitCast: {
     const Type *SrcTy = I->getOperand(0)->getType();
-    if (SrcTy->isInteger() || isa<PointerType>(SrcTy)) {
+    if ((SrcTy->isInteger() || isa<PointerType>(SrcTy)) &&
+        // TODO: For now, not handling conversions like:
+        // (bitcast i64 %x to <2 x i32>)
+        !isa<VectorType>(I->getType())) {
       ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, TD,
                         Depth+1);
       return;
diff --git a/test/Transforms/InstCombine/2009-07-02-MaskedIntVector.ll b/test/Transforms/InstCombine/2009-07-02-MaskedIntVector.ll
new file mode 100644
index 00000000000..7505de17a7a
--- /dev/null
+++ b/test/Transforms/InstCombine/2009-07-02-MaskedIntVector.ll
@@ -0,0 +1,15 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis
+; PR4495
+
+define i32 @test(i64 %test) {
+entry:
+	%0 = bitcast <4 x i32> undef to <16 x i8>		; <<16 x i8>> [#uses=1]
+	%t12 = shufflevector <16 x i8> %0, <16 x i8> zeroinitializer, <16 x i32> <i32 0, i32 16, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0>		; <<16 x i8>> [#uses=1]
+	%t11 = bitcast <16 x i8> %t12 to <2 x i64>		; <<2 x i64>> [#uses=1]
+	%t9 = extractelement <2 x i64> %t11, i32 0		; <i64> [#uses=1]
+	%t10 = bitcast i64 %t9 to <2 x i32>		; <<2 x i32>> [#uses=1]
+	%t7 = bitcast i64 %test to <2 x i32>		; <<2 x i32>> [#uses=1]
+	%t6 = xor <2 x i32> %t10, %t7		; <<2 x i32>> [#uses=1]
+	%t1 = extractelement <2 x i32> %t6, i32 0		; <i32> [#uses=1]
+	ret i32 %t1
+}