Index: lib/Analysis/InstructionSimplify.cpp
===================================================================
--- lib/Analysis/InstructionSimplify.cpp
+++ lib/Analysis/InstructionSimplify.cpp
@@ -3416,7 +3416,10 @@
   if (!match(CondVal, m_ICmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS))))
     return nullptr;
 
-  unsigned BitWidth = Q.DL.getTypeSizeInBits(TrueVal->getType());
+  // FIXME: This code is nearly duplicated in InstCombine. Using/refactoring
+  // decomposeBitTestICmp() might help.
+  unsigned BitWidth =
+      Q.DL.getTypeSizeInBits(TrueVal->getType()->getScalarType());
   APInt MinSignedValue = APInt::getSignBit(BitWidth);
   if (ICmpInst::isEquality(Pred) && match(CmpRHS, m_Zero())) {
     Value *X;
Index: lib/Transforms/InstCombine/InstCombineSelect.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -553,8 +553,11 @@
     }
   }
 
+  // FIXME: This code is nearly duplicated in InstSimplify. Using/refactoring
+  // decomposeBitTestICmp() might help.
   {
-    unsigned BitWidth = DL.getTypeSizeInBits(TrueVal->getType());
+    unsigned BitWidth =
+        DL.getTypeSizeInBits(TrueVal->getType()->getScalarType());
     APInt MinSignedValue = APInt::getSignBit(BitWidth);
     Value *X;
     const APInt *Y, *C;
Index: test/Transforms/InstCombine/select.ll
===================================================================
--- test/Transforms/InstCombine/select.ll
+++ test/Transforms/InstCombine/select.ll
@@ -1742,3 +1742,26 @@
   %s1 = select i1 %c1, i32 %s0, i32 -1
   ret i32 %s1
 }
+
+define i32 @select_icmp_slt0_xor(i32 %x) {
+; CHECK-LABEL: @select_icmp_slt0_xor(
+; CHECK-NEXT:    [[TMP1:%.*]] = or i32 %x, -2147483648
+; CHECK-NEXT:    ret i32 [[TMP1]]
+;
+  %cmp = icmp slt i32 %x, zeroinitializer
+  %xor = xor i32 %x, 2147483648
+  %x.xor = select i1 %cmp, i32 %x, i32 %xor
+  ret i32 %x.xor
+}
+
+define <2 x i32> @select_icmp_slt0_xor_vec(<2 x i32> %x) {
+; CHECK-LABEL: @select_icmp_slt0_xor_vec(
+; CHECK-NEXT:    [[TMP1:%.*]] = or <2 x i32> %x, <i32 -2147483648, i32 -2147483648>
+; CHECK-NEXT:    ret <2 x i32> [[TMP1]]
+;
+  %cmp = icmp slt <2 x i32> %x, zeroinitializer
+  %xor = xor <2 x i32> %x, <i32 2147483648, i32 2147483648>
+  %x.xor = select <2 x i1> %cmp, <2 x i32> %x, <2 x i32> %xor
+  ret <2 x i32> %x.xor
+}
+
Index: test/Transforms/InstSimplify/select.ll
===================================================================
--- test/Transforms/InstSimplify/select.ll
+++ test/Transforms/InstSimplify/select.ll
@@ -119,6 +119,17 @@
   ret i32 %cond
 }
 
+define <2 x i8> @test11vec(<2 x i8> %X) {
+; CHECK-LABEL: @test11vec(
+; CHECK-NEXT:    [[AND:%.*]] = and <2 x i8> %X, <i8 127, i8 127>
+; CHECK-NEXT:    ret <2 x i8> [[AND]]
+;
+  %cmp = icmp sgt <2 x i8> %X, <i8 -1, i8 -1>
+  %and = and <2 x i8> %X, <i8 127, i8 127>
+  %sel = select <2 x i1> %cmp, <2 x i8> %X, <2 x i8> %and
+  ret <2 x i8> %sel
+}
+
 define i32 @select_icmp_and_8_eq_0_or_8(i32 %x) {
 ; CHECK-LABEL: @select_icmp_and_8_eq_0_or_8(
 ; CHECK-NEXT:    [[OR:%.*]] = or i32 %x, 8