diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -140,7 +140,7 @@
   return nullptr;
 }
 
-/// Reduce integer multiplication patterns that contain a (1 << Z) factor.
+/// Reduce integer multiplication patterns that contain a (+/-1 << Z) factor.
 /// Callers are expected to call this twice to handle commuted patterns.
 static Value *foldMulShl1(BinaryOperator &Mul, bool CommuteOperands,
                           InstCombiner::BuilderTy &Builder) {
@@ -171,6 +171,17 @@
     return Builder.CreateAdd(Shl, FrX, Mul.getName(), HasNUW, PropagateNSW);
   }
 
+  // Similar to above, but a decrement of the shifted value is disguised as
+  // 'not' and becomes a sub:
+  // X * (~(-1 << Z)) --> X * ((1 << Z) - 1) --> (X << Z) - X
+  // This increases uses of X, so it may require a freeze, but that is still
+  // expected to be an improvement because it removes the multiply.
+  if (match(Y, m_OneUse(m_Not(m_OneUse(m_Shl(m_AllOnes(), m_Value(Z))))))) {
+    Value *FrX = Builder.CreateFreeze(X, X->getName() + ".fr");
+    Value *Shl = Builder.CreateShl(FrX, Z, "mulshl");
+    return Builder.CreateSub(Shl, FrX, Mul.getName());
+  }
+
   return nullptr;
 }
 
diff --git a/llvm/test/Transforms/InstCombine/mul.ll b/llvm/test/Transforms/InstCombine/mul.ll
--- a/llvm/test/Transforms/InstCombine/mul.ll
+++ b/llvm/test/Transforms/InstCombine/mul.ll
@@ -227,12 +227,14 @@
   ret i32 %m
 }
 
+; ((-1 << x) ^ -1) * y --> (y << x) - y
+
 define i8 @shl1_decrement(i8 %x, i8 %y) {
 ; CHECK-LABEL: @shl1_decrement(
-; CHECK-NEXT:    [[POW2X:%.*]] = shl i8 -1, [[X:%.*]]
-; CHECK-NEXT:    [[X1:%.*]] = xor i8 [[POW2X]], -1
-; CHECK-NEXT:    [[M:%.*]] = mul i8 [[X1]], [[Y:%.*]]
-; CHECK-NEXT:    ret i8 [[M]]
+; CHECK-NEXT:    [[Y_FR:%.*]] = freeze i8 [[Y:%.*]]
+; CHECK-NEXT:    [[MULSHL:%.*]] = shl i8 [[Y_FR]], [[X:%.*]]
+; CHECK-NEXT:    [[M1:%.*]] = sub i8 [[MULSHL]], [[Y_FR]]
+; CHECK-NEXT:    ret i8 [[M1]]
 ;
   %pow2x = shl i8 -1, %x
   %x1 = xor i8 %pow2x, -1
@@ -243,10 +245,9 @@
 define i8 @shl1_decrement_commute(i8 %x, i8 noundef %p) {
 ; CHECK-LABEL: @shl1_decrement_commute(
 ; CHECK-NEXT:    [[Y:%.*]] = ashr i8 [[P:%.*]], 1
-; CHECK-NEXT:    [[NOTMASK:%.*]] = shl nsw i8 -1, [[X:%.*]]
-; CHECK-NEXT:    [[X1:%.*]] = xor i8 [[NOTMASK]], -1
-; CHECK-NEXT:    [[M:%.*]] = mul i8 [[Y]], [[X1]]
-; CHECK-NEXT:    ret i8 [[M]]
+; CHECK-NEXT:    [[MULSHL:%.*]] = shl i8 [[Y]], [[X:%.*]]
+; CHECK-NEXT:    [[M1:%.*]] = sub i8 [[MULSHL]], [[Y]]
+; CHECK-NEXT:    ret i8 [[M1]]
 ;
   %y = ashr i8 %p, 1 ; thwart complexity-based canonicalization
   %pow2x = shl i8 1, %x
@@ -257,10 +258,10 @@
 
 define i8 @shl1_nuw_decrement(i8 %x, i8 %y) {
 ; CHECK-LABEL: @shl1_nuw_decrement(
-; CHECK-NEXT:    [[POW2X:%.*]] = shl i8 -1, [[X:%.*]]
-; CHECK-NEXT:    [[X1:%.*]] = xor i8 [[POW2X]], -1
-; CHECK-NEXT:    [[M:%.*]] = mul nuw i8 [[X1]], [[Y:%.*]]
-; CHECK-NEXT:    ret i8 [[M]]
+; CHECK-NEXT:    [[Y_FR:%.*]] = freeze i8 [[Y:%.*]]
+; CHECK-NEXT:    [[MULSHL:%.*]] = shl i8 [[Y_FR]], [[X:%.*]]
+; CHECK-NEXT:    [[M1:%.*]] = sub i8 [[MULSHL]], [[Y_FR]]
+; CHECK-NEXT:    ret i8 [[M1]]
 ;
   %pow2x = shl i8 -1, %x
   %x1 = xor i8 %pow2x, -1
@@ -270,10 +271,10 @@
 
 define i8 @shl1_nsw_decrement(i8 %x, i8 %y) {
 ; CHECK-LABEL: @shl1_nsw_decrement(
-; CHECK-NEXT:    [[POW2X:%.*]] = shl nsw i8 -1, [[X:%.*]]
-; CHECK-NEXT:    [[X1:%.*]] = xor i8 [[POW2X]], -1
-; CHECK-NEXT:    [[M:%.*]] = mul nsw i8 [[X1]], [[Y:%.*]]
-; CHECK-NEXT:    ret i8 [[M]]
+; CHECK-NEXT:    [[Y_FR:%.*]] = freeze i8 [[Y:%.*]]
+; CHECK-NEXT:    [[MULSHL:%.*]] = shl i8 [[Y_FR]], [[X:%.*]]
+; CHECK-NEXT:    [[M1:%.*]] = sub i8 [[MULSHL]], [[Y_FR]]
+; CHECK-NEXT:    ret i8 [[M1]]
 ;
   %pow2x = shl nsw i8 -1, %x
   %x1 = xor i8 %pow2x, -1
@@ -281,6 +282,8 @@
   ret i8 %m
 }
 
+; negative test - extra use would require more instructions
+
 define i32 @shl1_decrement_use(i32 %x, i32 %y) {
 ; CHECK-LABEL: @shl1_decrement_use(
 ; CHECK-NEXT:    [[NOTMASK:%.*]] = shl nsw i32 -1, [[X:%.*]]
@@ -296,12 +299,13 @@
   ret i32 %m
 }
 
+; the fold works for vectors too and if 'y' is a constant, sub becomes add
+
 define <2 x i8> @shl1_decrement_vec(<2 x i8> %x) {
 ; CHECK-LABEL: @shl1_decrement_vec(
-; CHECK-NEXT:    [[POW2X:%.*]] = shl <2 x i8> <i8 -1, i8 -1>, [[X:%.*]]
-; CHECK-NEXT:    [[X1:%.*]] = xor <2 x i8> [[POW2X]], <i8 -1, i8 -1>
-; CHECK-NEXT:    [[M:%.*]] = mul <2 x i8> [[X1]], <i8 42, i8 -3>
-; CHECK-NEXT:    ret <2 x i8> [[M]]
+; CHECK-NEXT:    [[MULSHL:%.*]] = shl <2 x i8> <i8 42, i8 -3>, [[X:%.*]]
+; CHECK-NEXT:    [[M1:%.*]] = add <2 x i8> [[MULSHL]], <i8 -42, i8 3>
+; CHECK-NEXT:    ret <2 x i8> [[M1]]
 ;
   %pow2x = shl <2 x i8> <i8 -1, i8 -1>, %x
   %x1 = xor <2 x i8> %pow2x, <i8 -1, i8 -1>