Index: llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -1314,6 +1314,17 @@
   // X % C0 + (( X / C0 ) % C1) * C0 => X % (C0 * C1)
   if (Value *V = SimplifyAddWithRemainder(I)) return replaceInstUsesWith(I, V);
 
+  // ((X s/ C1) << C2) + X => X s% -C1 where -C1 is 1 << C2
+  const APInt *C1, *C2;
+  if (match(LHS, m_Shl(m_SDiv(m_Specific(RHS), m_APInt(C1)), m_APInt(C2)))) {
+    APInt one(C2->getBitWidth(), 1);
+    APInt minusC1 = -(*C1);
+    if (minusC1 == (one << *C2)) {
+      Constant *NewRHS = ConstantInt::get(RHS->getType(), minusC1);
+      return BinaryOperator::CreateSRem(RHS, NewRHS);
+    }
+  }
+
   // A+B --> A|B iff A and B have no bits set in common.
   if (haveNoCommonBitsSet(LHS, RHS, DL, &AC, &I, &DT))
     return BinaryOperator::CreateOr(LHS, RHS);
Index: llvm/test/Transforms/InstCombine/add-shl-sdiv-to-srem.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/InstCombine/add-shl-sdiv-to-srem.ll
@@ -0,0 +1,262 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+define i8 @add-shl-sdiv-scalar0(i8 %x) {
+; CHECK-LABEL: @add-shl-sdiv-scalar0(
+; CHECK-NEXT:    [[RZ:%.*]] = srem i8 [[X:%.*]], 4
+; CHECK-NEXT:    ret i8 [[RZ]]
+;
+  %sd = sdiv i8 %x, -4
+  %sl = shl i8 %sd, 2
+  %rz = add i8 %sl, %x
+  ret i8 %rz
+}
+
+define i8 @add-shl-sdiv-scalar1(i8 %x) {
+; CHECK-LABEL: @add-shl-sdiv-scalar1(
+; CHECK-NEXT:    [[RZ:%.*]] = srem i8 [[X:%.*]], 64
+; CHECK-NEXT:    ret i8 [[RZ]]
+;
+  %sd = sdiv i8 %x, -64
+  %sl = shl i8 %sd, 6
+  %rz = add i8 %sl, %x
+  ret i8 %rz
+}
+
+define i32 @add-shl-sdiv-scalar2(i32 %x) {
+; CHECK-LABEL: @add-shl-sdiv-scalar2(
+; CHECK-NEXT:    [[RZ:%.*]] = srem i32 [[X:%.*]], 1073741824
+; CHECK-NEXT:    ret i32 [[RZ]]
+;
+  %sd = sdiv i32 %x, -1073741824
+  %sl = shl i32 %sd, 30
+  %rz = add i32 %sl, %x
+  ret i32 %rz
+}
+
+; Splat vectors
+
+define <3 x i8> @add-shl-sdiv-splat0(<3 x i8> %x) {
+; CHECK-LABEL: @add-shl-sdiv-splat0(
+; CHECK-NEXT:    [[RZ:%.*]] = srem <3 x i8> [[X:%.*]], <i8 4, i8 4, i8 4>
+; CHECK-NEXT:    ret <3 x i8> [[RZ]]
+;
+  %sd = sdiv <3 x i8> %x, <i8 -4, i8 -4, i8 -4>
+  %sl = shl <3 x i8> %sd, <i8 2, i8 2, i8 2>
+  %rz = add <3 x i8> %sl, %x
+  ret <3 x i8> %rz
+}
+
+define <4 x i32> @add-shl-sdiv-splat1(<4 x i32> %x) {
+; CHECK-LABEL: @add-shl-sdiv-splat1(
+; CHECK-NEXT:    [[RZ:%.*]] = srem <4 x i32> [[X:%.*]], <i32 1073741824, i32 1073741824, i32 1073741824, i32 1073741824>
+; CHECK-NEXT:    ret <4 x i32> [[RZ]]
+;
+  %sd = sdiv <4 x i32> %x, <i32 -1073741824, i32 -1073741824, i32 -1073741824, i32 -1073741824>
+  %sl = shl <4 x i32> %sd, <i32 30, i32 30, i32 30, i32 30>
+  %rz = add <4 x i32> %sl, %x
+  ret <4 x i32> %rz
+}
+
+define <2 x i64> @add-shl-sdiv-splat2(<2 x i64> %x) {
+; CHECK-LABEL: @add-shl-sdiv-splat2(
+; CHECK-NEXT:    [[RZ:%.*]] = srem <2 x i64> [[X:%.*]], <i64 32, i64 32>
+; CHECK-NEXT:    ret <2 x i64> [[RZ]]
+;
+  %sd = sdiv <2 x i64> %x, <i64 -32, i64 -32>
+  %sl = shl <2 x i64> %sd, <i64 5, i64 5>
+  %rz = add <2 x i64> %sl, %x
+  ret <2 x i64> %rz
+}
+
+; One-use tests
+
+declare void @use32(i32)
+define i32 @add-shl-sdiv-i32-4-use0(i32 %x) {
+; CHECK-LABEL: @add-shl-sdiv-i32-4-use0(
+; CHECK-NEXT:    call void @use32(i32 [[X:%.*]])
+; CHECK-NEXT:    [[RZ:%.*]] = srem i32 [[X]], 16
+; CHECK-NEXT:    ret i32 [[RZ]]
+;
+  call void @use32(i32 %x)
+  %sd = sdiv i32 %x, -16
+  %sl = shl i32 %sd, 4
+  %rz = add i32 %sl, %x
+  ret i32 %rz
+}
+
+define i32 @add-shl-sdiv-i32-use1(i32 %x) {
+; CHECK-LABEL: @add-shl-sdiv-i32-use1(
+; CHECK-NEXT:    [[SD:%.*]] = sdiv i32 [[X:%.*]], -16
+; CHECK-NEXT:    call void @use32(i32 [[SD]])
+; CHECK-NEXT:    [[RZ:%.*]] = srem i32 [[X]], 16
+; CHECK-NEXT:    ret i32 [[RZ]]
+;
+  %sd = sdiv i32 %x, -16
+  call void @use32(i32 %sd)
+  %sl = shl i32 %sd, 4
+  %rz = add i32 %sl, %x
+  ret i32 %rz
+}
+
+define i32 @add-shl-sdiv-i32-use2(i32 %x) {
+; CHECK-LABEL: @add-shl-sdiv-i32-use2(
+; CHECK-NEXT:    [[SD:%.*]] = sdiv i32 [[X:%.*]], -16
+; CHECK-NEXT:    [[SL:%.*]] = shl i32 [[SD]], 4
+; CHECK-NEXT:    call void @use32(i32 [[SL]])
+; CHECK-NEXT:    [[RZ:%.*]] = srem i32 [[X]], 16
+; CHECK-NEXT:    ret i32 [[RZ]]
+;
+  %sd = sdiv i32 %x, -16
+  %sl = shl i32 %sd, 4
+  call void @use32(i32 %sl)
+  %rz = add i32 %sl, %x
+  ret i32 %rz
+}
+
+define i32 @add-shl-sdiv-i32-use3(i32 %x) {
+; CHECK-LABEL: @add-shl-sdiv-i32-use3(
+; CHECK-NEXT:    [[SD:%.*]] = sdiv i32 [[X:%.*]], -16
+; CHECK-NEXT:    call void @use32(i32 [[SD]])
+; CHECK-NEXT:    [[SL:%.*]] = shl i32 [[SD]], 4
+; CHECK-NEXT:    call void @use32(i32 [[SL]])
+; CHECK-NEXT:    [[RZ:%.*]] = srem i32 [[X]], 16
+; CHECK-NEXT:    ret i32 [[RZ]]
+;
+  %sd = sdiv i32 %x, -16
+  call void @use32(i32 %sd)
+  %sl = shl i32 %sd, 4
+  call void @use32(i32 %sl)
+  %rz = add i32 %sl, %x
+  ret i32 %rz
+}
+
+declare void @use3xi8(<3 x i8>)
+define <3 x i8> @add-shl-sdiv-use4(<3 x i8> %x) {
+; CHECK-LABEL: @add-shl-sdiv-use4(
+; CHECK-NEXT:    [[SD:%.*]] = sdiv <3 x i8> [[X:%.*]], <i8 -4, i8 -4, i8 -4>
+; CHECK-NEXT:    call void @use3xi8(<3 x i8> [[SD]])
+; CHECK-NEXT:    [[RZ:%.*]] = srem <3 x i8> [[X]], <i8 4, i8 4, i8 4>
+; CHECK-NEXT:    ret <3 x i8> [[RZ]]
+;
+  %sd = sdiv <3 x i8> %x, <i8 -4, i8 -4, i8 -4>
+  call void @use3xi8(<3 x i8> %sd)
+  %sl = shl <3 x i8> %sd, <i8 2, i8 2, i8 2>
+  %rz = add <3 x i8> %sl, %x
+  ret <3 x i8> %rz
+}
+
+; Negative
+
+define i8 @add-shl-sdiv-negative0(i8 %x) {
+; CHECK-LABEL: @add-shl-sdiv-negative0(
+; CHECK-NEXT:    [[SD:%.*]] = sdiv i8 [[X:%.*]], 4
+; CHECK-NEXT:    [[SL:%.*]] = shl nsw i8 [[SD]], 2
+; CHECK-NEXT:    [[RZ:%.*]] = add i8 [[SL]], [[X]]
+; CHECK-NEXT:    ret i8 [[RZ]]
+;
+  %sd = sdiv i8 %x, 4
+  %sl = shl i8 %sd, 2
+  %rz = add i8 %sl, %x
+  ret i8 %rz
+}
+
+define i32 @add-shl-sdiv-negative1(i32 %x) {
+; CHECK-LABEL: @add-shl-sdiv-negative1(
+; CHECK-NEXT:    [[RZ:%.*]] = sub i32 0, [[X:%.*]]
+; CHECK-NEXT:    ret i32 [[RZ]]
+;
+  %sd = sdiv i32 %x, -1
+  %sl = shl i32 %sd, 1
+  %rz = add i32 %sl, %x
+  ret i32 %rz
+}
+
+define i32 @add-shl-sdiv-negative2(i32 %x) {
+; CHECK-LABEL: @add-shl-sdiv-negative2(
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i32 [[X:%.*]], -2147483648
+; CHECK-NEXT:    [[SL:%.*]] = select i1 [[TMP1]], i32 -2147483648, i32 0
+; CHECK-NEXT:    [[RZ:%.*]] = add i32 [[SL]], [[X]]
+; CHECK-NEXT:    ret i32 [[RZ]]
+;
+  %sd = sdiv i32 %x, -2147483648
+  %sl = shl i32 %sd, 31
+  %rz = add i32 %sl, %x
+  ret i32 %rz
+}
+
+define <3 x i8> @add-shl-sdiv-negative3(<3 x i8> %x) {
+; CHECK-LABEL: @add-shl-sdiv-negative3(
+; CHECK-NEXT:    [[SD:%.*]] = sdiv <3 x i8> [[X:%.*]], <i8 -5, i8 -5, i8 -5>
+; CHECK-NEXT:    [[SL:%.*]] = shl <3 x i8> [[SD]], <i8 2, i8 2, i8 2>
+; CHECK-NEXT:    [[RZ:%.*]] = add <3 x i8> [[SL]], [[X]]
+; CHECK-NEXT:    ret <3 x i8> [[RZ]]
+;
+  %sd = sdiv <3 x i8> %x, <i8 -5, i8 -5, i8 -5>
+  %sl = shl <3 x i8> %sd, <i8 2, i8 2, i8 2>
+  %rz = add <3 x i8> %sl, %x
+  ret <3 x i8> %rz
+}
+
+define <2 x i64> @add-shl-sdiv-negative4(<2 x i64> %x) {
+; CHECK-LABEL: @add-shl-sdiv-negative4(
+; CHECK-NEXT:    ret <2 x i64> undef
+;
+  %sd = sdiv <2 x i64> %x, <i64 32, i64 32>
+  %sl = shl <2 x i64> %sd, <i64 -5, i64 -5>
+  %rz = add <2 x i64> %sl, %x
+  ret <2 x i64> %rz
+}
+
+; Vectors with undef values
+
+define <3 x i8> @add-shl-sdiv-3xi8-undef0(<3 x i8> %x) {
+; CHECK-LABEL: @add-shl-sdiv-3xi8-undef0(
+; CHECK-NEXT:    ret <3 x i8> [[X:%.*]]
+;
+  %sd = sdiv <3 x i8> %x, <i8 -4, i8 undef, i8 -4>
+  %sl = shl <3 x i8> %sd, <i8 2, i8 2, i8 2>
+  %rz = add <3 x i8> %sl, %x
+  ret <3 x i8> %rz
+}
+
+define <3 x i8> @add-shl-sdiv-3xi8-undef1(<3 x i8> %x) {
+; CHECK-LABEL: @add-shl-sdiv-3xi8-undef1(
+; CHECK-NEXT:    [[SD:%.*]] = sdiv <3 x i8> [[X:%.*]], <i8 -4, i8 -4, i8 -4>
+; CHECK-NEXT:    [[SL:%.*]] = shl <3 x i8> [[SD]], <i8 2, i8 undef, i8 2>
+; CHECK-NEXT:    [[RZ:%.*]] = add <3 x i8> [[SL]], [[X]]
+; CHECK-NEXT:    ret <3 x i8> [[RZ]]
+;
+  %sd = sdiv <3 x i8> %x, <i8 -4, i8 -4, i8 -4>
+  %sl = shl <3 x i8> %sd, <i8 2, i8 undef, i8 2>
+  %rz = add <3 x i8> %sl, %x
+  ret <3 x i8> %rz
+}
+
+; Non-splat vectors
+
+define <2 x i64> @add-shl-sdiv-nonsplat0(<2 x i64> %x) {
+; CHECK-LABEL: @add-shl-sdiv-nonsplat0(
+; CHECK-NEXT:    [[SD:%.*]] = sdiv <2 x i64> [[X:%.*]], <i64 -32, i64 -64>
+; CHECK-NEXT:    [[SL:%.*]] = shl <2 x i64> [[SD]], <i64 5, i64 6>
+; CHECK-NEXT:    [[RZ:%.*]] = add <2 x i64> [[SL]], [[X]]
+; CHECK-NEXT:    ret <2 x i64> [[RZ]]
+;
+  %sd = sdiv <2 x i64> %x, <i64 -32, i64 -64>
+  %sl = shl <2 x i64> %sd, <i64 5, i64 6>
+  %rz = add <2 x i64> %sl, %x
+  ret <2 x i64> %rz
+}
+
+define <3 x i8> @add-shl-sdiv-nonsplat1(<3 x i8> %x) {
+; CHECK-LABEL: @add-shl-sdiv-nonsplat1(
+; CHECK-NEXT:    [[SD:%.*]] = sdiv <3 x i8> [[X:%.*]], <i8 -4, i8 -4, i8 -4>
+; CHECK-NEXT:    [[SL:%.*]] = shl <3 x i8> [[SD]], <i8 2, i8 2, i8 3>
+; CHECK-NEXT:    [[RZ:%.*]] = add <3 x i8> [[SL]], [[X]]
+; CHECK-NEXT:    ret <3 x i8> [[RZ]]
+;
+  %sd = sdiv <3 x i8> %x, <i8 -4, i8 -4, i8 -4>
+  %sl = shl <3 x i8> %sd, <i8 2, i8 2, i8 3>
+  %rz = add <3 x i8> %sl, %x
+  ret <3 x i8> %rz
+}