Index: llvm/lib/Analysis/InstructionSimplify.cpp
===================================================================
--- llvm/lib/Analysis/InstructionSimplify.cpp
+++ llvm/lib/Analysis/InstructionSimplify.cpp
@@ -2414,6 +2414,24 @@
       match(Op1, m_Not(m_Specific(Op0))))
     return Constant::getAllOnesValue(Op0->getType());
 
+  // (~A | B) ^ (A & B) --> ~A -- There are 8 commuted variants.
+  // The 'not' op must contain a complete -1 operand (no undef elements for
+  // vector) for the transform to be safe.
+  auto matchNotA = [](Value *X, Value *Y) -> Value * {
+    Value *A, *B, *NotA;
+    const APInt *C;
+    if (match(X, m_c_Or(m_CombineAnd(m_Xor(m_Value(A), m_APIntForbidUndef(C)),
+                                     m_Value(NotA)),
+                        m_Value(B))) &&
+        match(Y, m_c_And(m_Specific(A), m_Specific(B))) && C->isAllOnes())
+      return NotA;
+    return nullptr;
+  };
+  if (Value *NotA = matchNotA(Op0, Op1))
+    return NotA;
+  if (Value *NotA = matchNotA(Op1, Op0))
+    return NotA;
+
   if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Xor))
     return V;
 
Index: llvm/test/Transforms/InstSimplify/xor.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/xor.ll
+++ llvm/test/Transforms/InstSimplify/xor.ll
@@ -11,11 +11,8 @@
 
 define i4 @xor_and_or_not_commute0(i4 %a, i4 %b) {
 ; CHECK-LABEL: @xor_and_or_not_commute0(
-; CHECK-NEXT:    [[AND:%.*]] = and i4 [[A:%.*]], [[B:%.*]]
-; CHECK-NEXT:    [[NOT:%.*]] = xor i4 [[A]], -1
-; CHECK-NEXT:    [[OR:%.*]] = or i4 [[NOT]], [[B]]
-; CHECK-NEXT:    [[R:%.*]] = xor i4 [[AND]], [[OR]]
-; CHECK-NEXT:    ret i4 [[R]]
+; CHECK-NEXT:    [[NOT:%.*]] = xor i4 [[A:%.*]], -1
+; CHECK-NEXT:    ret i4 [[NOT]]
 ;
   %and = and i4 %a, %b
   %not = xor i4 %a, -1
@@ -26,11 +23,8 @@
 
 define <2 x i4> @xor_and_or_not_commute1(<2 x i4> %a, <2 x i4> %b) {
 ; CHECK-LABEL: @xor_and_or_not_commute1(
-; CHECK-NEXT:    [[AND:%.*]] = and <2 x i4> [[A:%.*]], [[B:%.*]]
-; CHECK-NEXT:    [[NOT:%.*]] = xor <2 x i4> [[A]], <i4 -1, i4 -1>
-; CHECK-NEXT:    [[OR:%.*]] = or <2 x i4> [[NOT]], [[B]]
-; CHECK-NEXT:    [[R:%.*]] = xor <2 x i4> [[OR]], [[AND]]
-; CHECK-NEXT:    ret <2 x i4> [[R]]
+; CHECK-NEXT:    [[NOT:%.*]] = xor <2 x i4> [[A:%.*]], <i4 -1, i4 -1>
+; CHECK-NEXT:    ret <2 x i4> [[NOT]]
 ;
   %and = and <2 x i4> %a, %b
   %not = xor <2 x i4> %a, <i4 -1, i4 -1>
@@ -41,11 +35,8 @@
 
 define i74 @xor_and_or_not_commute2(i74 %a, i74 %b) {
 ; CHECK-LABEL: @xor_and_or_not_commute2(
-; CHECK-NEXT:    [[AND:%.*]] = and i74 [[B:%.*]], [[A:%.*]]
-; CHECK-NEXT:    [[NOT:%.*]] = xor i74 [[A]], -1
-; CHECK-NEXT:    [[OR:%.*]] = or i74 [[NOT]], [[B]]
-; CHECK-NEXT:    [[R:%.*]] = xor i74 [[AND]], [[OR]]
-; CHECK-NEXT:    ret i74 [[R]]
+; CHECK-NEXT:    [[NOT:%.*]] = xor i74 [[A:%.*]], -1
+; CHECK-NEXT:    ret i74 [[NOT]]
 ;
   %and = and i74 %b, %a
   %not = xor i74 %a, -1
@@ -56,11 +47,8 @@
 
 define <2 x i4> @xor_and_or_not_commute3(<2 x i4> %a, <2 x i4> %b) {
 ; CHECK-LABEL: @xor_and_or_not_commute3(
-; CHECK-NEXT:    [[AND:%.*]] = and <2 x i4> [[B:%.*]], [[A:%.*]]
-; CHECK-NEXT:    [[NOT:%.*]] = xor <2 x i4> [[A]], <i4 -1, i4 -1>
-; CHECK-NEXT:    [[OR:%.*]] = or <2 x i4> [[NOT]], [[B]]
-; CHECK-NEXT:    [[R:%.*]] = xor <2 x i4> [[OR]], [[AND]]
-; CHECK-NEXT:    ret <2 x i4> [[R]]
+; CHECK-NEXT:    [[NOT:%.*]] = xor <2 x i4> [[A:%.*]], <i4 -1, i4 -1>
+; CHECK-NEXT:    ret <2 x i4> [[NOT]]
 ;
   %and = and <2 x i4> %b, %a
   %not = xor <2 x i4> %a, <i4 -1, i4 -1>
@@ -71,11 +59,8 @@
 
 define i8 @xor_and_or_not_commute4(i8 %a, i8 %b) {
 ; CHECK-LABEL: @xor_and_or_not_commute4(
-; CHECK-NEXT:    [[AND:%.*]] = and i8 [[A:%.*]], [[B:%.*]]
-; CHECK-NEXT:    [[NOT:%.*]] = xor i8 [[A]], -1
-; CHECK-NEXT:    [[OR:%.*]] = or i8 [[B]], [[NOT]]
-; CHECK-NEXT:    [[R:%.*]] = xor i8 [[AND]], [[OR]]
-; CHECK-NEXT:    ret i8 [[R]]
+; CHECK-NEXT:    [[NOT:%.*]] = xor i8 [[A:%.*]], -1
+; CHECK-NEXT:    ret i8 [[NOT]]
 ;
   %and = and i8 %a, %b
   %not = xor i8 %a, -1
@@ -86,11 +71,8 @@
 
 define i8 @xor_and_or_not_commute5(i8 %a, i8 %b) {
 ; CHECK-LABEL: @xor_and_or_not_commute5(
-; CHECK-NEXT:    [[AND:%.*]] = and i8 [[A:%.*]], [[B:%.*]]
-; CHECK-NEXT:    [[NOT:%.*]] = xor i8 [[A]], -1
-; CHECK-NEXT:    [[OR:%.*]] = or i8 [[B]], [[NOT]]
-; CHECK-NEXT:    [[R:%.*]] = xor i8 [[OR]], [[AND]]
-; CHECK-NEXT:    ret i8 [[R]]
+; CHECK-NEXT:    [[NOT:%.*]] = xor i8 [[A:%.*]], -1
+; CHECK-NEXT:    ret i8 [[NOT]]
 ;
   %and = and i8 %a, %b
   %not = xor i8 %a, -1
@@ -101,11 +83,8 @@
 
 define i8 @xor_and_or_not_commute6(i8 %a, i8 %b) {
 ; CHECK-LABEL: @xor_and_or_not_commute6(
-; CHECK-NEXT:    [[AND:%.*]] = and i8 [[B:%.*]], [[A:%.*]]
-; CHECK-NEXT:    [[NOT:%.*]] = xor i8 [[A]], -1
-; CHECK-NEXT:    [[OR:%.*]] = or i8 [[B]], [[NOT]]
-; CHECK-NEXT:    [[R:%.*]] = xor i8 [[AND]], [[OR]]
-; CHECK-NEXT:    ret i8 [[R]]
+; CHECK-NEXT:    [[NOT:%.*]] = xor i8 [[A:%.*]], -1
+; CHECK-NEXT:    ret i8 [[NOT]]
 ;
   %and = and i8 %b, %a
   %not = xor i8 %a, -1
@@ -116,11 +95,8 @@
 
 define i8 @xor_and_or_not_commute7(i8 %a, i8 %b) {
 ; CHECK-LABEL: @xor_and_or_not_commute7(
-; CHECK-NEXT:    [[AND:%.*]] = and i8 [[B:%.*]], [[A:%.*]]
-; CHECK-NEXT:    [[NOT:%.*]] = xor i8 [[A]], -1
-; CHECK-NEXT:    [[OR:%.*]] = or i8 [[B]], [[NOT]]
-; CHECK-NEXT:    [[R:%.*]] = xor i8 [[OR]], [[AND]]
-; CHECK-NEXT:    ret i8 [[R]]
+; CHECK-NEXT:    [[NOT:%.*]] = xor i8 [[A:%.*]], -1
+; CHECK-NEXT:    ret i8 [[NOT]]
 ;
   %and = and i8 %b, %a
   %not = xor i8 %a, -1
@@ -129,6 +105,8 @@
   ret i8 %r
 }
 
+; negative test - must match specific values
+
 define i4 @xor_and_or_not_wrong_val1(i4 %a, i4 %b, i4 %c) {
 ; CHECK-LABEL: @xor_and_or_not_wrong_val1(
 ; CHECK-NEXT:    [[AND:%.*]] = and i4 [[A:%.*]], [[C:%.*]]
@@ -144,6 +122,8 @@
   ret i4 %r
 }
 
+; negative test - must match specific values
+
 define i4 @xor_and_or_not_wrong_val2(i4 %a, i4 %b, i4 %c) {
 ; CHECK-LABEL: @xor_and_or_not_wrong_val2(
 ; CHECK-NEXT:    [[AND:%.*]] = and i4 [[C:%.*]], [[B:%.*]]
@@ -159,6 +139,8 @@
   ret i4 %r
 }
 
+; negative test - incorrect to propagate undef element
+
 define <2 x i4> @xor_and_or_not_undef_elt(<2 x i4> %a, <2 x i4> %b) {
 ; CHECK-LABEL: @xor_and_or_not_undef_elt(
 ; CHECK-NEXT:    [[AND:%.*]] = and <2 x i4> [[B:%.*]], [[A:%.*]]