diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index e305041f7490..28363e2b9e88 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -4282,7 +4282,8 @@ unsigned SelectionDAG::ComputeNumSignBits(SDValue Op, const APInt &DemandedElts,
           // scalar cases.
           Type *CstTy = Cst->getType();
           if (CstTy->isVectorTy() &&
-              (NumElts * VTBits) == CstTy->getPrimitiveSizeInBits()) {
+              (NumElts * VTBits) == CstTy->getPrimitiveSizeInBits() &&
+              VTBits == CstTy->getScalarSizeInBits()) {
             Tmp = VTBits;
             for (unsigned i = 0; i != NumElts; ++i) {
               if (!DemandedElts[i])
diff --git a/llvm/test/CodeGen/X86/vselect-constants.ll b/llvm/test/CodeGen/X86/vselect-constants.ll
index 8aba81824d12..f95eccae188a 100644
--- a/llvm/test/CodeGen/X86/vselect-constants.ll
+++ b/llvm/test/CodeGen/X86/vselect-constants.ll
@@ -298,6 +298,8 @@ define i32 @wrong_min_signbits(<2 x i16> %x) {
 ; AVX-NEXT:    vpcmpeqw %xmm1, %xmm0, %xmm0
 ; AVX-NEXT:    vmovdqa {{.*#+}} xmm1 = [1,0,0,0]
 ; AVX-NEXT:    vpandn %xmm1, %xmm0, %xmm0
+; AVX-NEXT:    vpsllw $15, %xmm0, %xmm0
+; AVX-NEXT:    vpsraw $15, %xmm0, %xmm0
 ; AVX-NEXT:    vpblendvb %xmm0, {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1, %xmm0
 ; AVX-NEXT:    vmovd %xmm0, %eax
 ; AVX-NEXT:    retq