Index: llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -1786,6 +1786,17 @@
     return SelectInst::Create(Cmp, ConstantInt::getNullValue(Ty), Op0);
   }
 
+  // For "(X + 1) % Op1" and if (X u< Op1) => (X + 1) == Op1 ? 0 : X + 1 .
+  if (match(Op0, m_Add(m_Value(X), m_One()))) {
+    Value *Val =
+        simplifyICmpInst(ICmpInst::ICMP_ULT, X, Op1, SQ.getWithInstruction(&I));
+    if (Val && match(Val, m_One())) {
+      Value *FrozenOp0 = Builder.CreateFreeze(Op0, Op0->getName() + ".frozen");
+      Value *Cmp = Builder.CreateICmpEQ(FrozenOp0, Op1);
+      return SelectInst::Create(Cmp, ConstantInt::getNullValue(Ty), FrozenOp0);
+    }
+  }
+
   return nullptr;
 }
 
Index: llvm/test/Transforms/InstCombine/urem-via-cmp-select.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/InstCombine/urem-via-cmp-select.ll
@@ -0,0 +1,135 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+; https://alive2.llvm.org/ce/z/UNmz9j
+define noundef i64 @urem_assume(i64 noundef %x, i64 noundef %n) {
+; CHECK-LABEL: @urem_assume(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i64 [[X:%.*]], [[N:%.*]]
+; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
+; CHECK-NEXT:    [[ADD:%.*]] = add i64 [[X]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i64 [[ADD]], [[N]]
+; CHECK-NEXT:    [[OUT:%.*]] = select i1 [[TMP0]], i64 0, i64 [[ADD]]
+; CHECK-NEXT:    ret i64 [[OUT]]
+;
+start:
+  %cmp = icmp ult i64 %x, %n
+  tail call void @llvm.assume(i1 %cmp)
+  %add = add nuw i64 %x, 1
+  %out = urem i64 %add, %n
+  ret i64 %out
+}
+
+; https://alive2.llvm.org/ce/z/uo7HMz
+define noundef i64 @urem_assume_without_nuw(i64 %x, i64 %n) {
+; CHECK-LABEL: @urem_assume_without_nuw(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    [[X_FR:%.*]] = freeze i64 [[X:%.*]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i64 [[X_FR]], [[N:%.*]]
+; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
+; CHECK-NEXT:    [[ADD:%.*]] = add i64 [[X_FR]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i64 [[ADD]], [[N]]
+; CHECK-NEXT:    [[OUT:%.*]] = select i1 [[TMP0]], i64 0, i64 [[ADD]]
+; CHECK-NEXT:    ret i64 [[OUT]]
+;
+start:
+  %cmp = icmp ult i64 %x, %n
+  tail call void @llvm.assume(i1 %cmp)
+  %add = add i64 %x, 1
+  %out = urem i64 %add, %n
+  ret i64 %out
+}
+
+define noundef i64 @urem_assume_eq(i64 noundef %x, i64 noundef %n) {
+; CHECK-LABEL: @urem_assume_eq(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i64 [[X:%.*]], [[N:%.*]]
+; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
+; CHECK-NEXT:    [[ADD:%.*]] = add i64 [[X]], 1
+; CHECK-NEXT:    [[OUT:%.*]] = urem i64 [[ADD]], [[N]]
+; CHECK-NEXT:    ret i64 [[OUT]]
+;
+start:
+  %cmp = icmp eq i64 %x, %n
+  tail call void @llvm.assume(i1 %cmp)
+  %add = add i64 %x, 1
+  %out = urem i64 %add, %n
+  ret i64 %out
+}
+
+; Negative test: The assume is false
+define noundef i64 @urem_assume_ne(i64 noundef %x, i64 noundef %n) {
+; CHECK-LABEL: @urem_assume_ne(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i64 [[X:%.*]], [[N:%.*]]
+; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
+; CHECK-NEXT:    [[ADD:%.*]] = add i64 [[X]], 1
+; CHECK-NEXT:    [[OUT:%.*]] = urem i64 [[ADD]], [[N]]
+; CHECK-NEXT:    ret i64 [[OUT]]
+;
+start:
+  %cmp = icmp ne i64 %x, %n
+  tail call void @llvm.assume(i1 %cmp)
+  %add = add i64 %x, 1
+  %out = urem i64 %add, %n
+  ret i64 %out
+}
+
+; Negative test: The add constant is not 1
+define noundef i64 @urem_assume_with_unexpected_const(i64 %x, i64 %n) {
+; CHECK-LABEL: @urem_assume_with_unexpected_const(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i64 [[X:%.*]], [[N:%.*]]
+; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
+; CHECK-NEXT:    [[ADD:%.*]] = add i64 [[X]], 2
+; CHECK-NEXT:    [[OUT:%.*]] = urem i64 [[ADD]], [[N]]
+; CHECK-NEXT:    ret i64 [[OUT]]
+;
+start:
+  %cmp = icmp ult i64 %x, %n
+  tail call void @llvm.assume(i1 %cmp)
+  %add = add i64 %x, 2            ; Transform only when the constant is 1
+  %out = urem i64 %add, %n
+  ret i64 %out
+}
+
+; Negative test: Need a dominating condition or assume
+define noundef i64 @urem_without_assume(i64 %x, i64 %n) {
+; CHECK-LABEL: @urem_without_assume(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    [[ADD:%.*]] = add i64 [[X:%.*]], 1
+; CHECK-NEXT:    [[OUT:%.*]] = urem i64 [[ADD]], [[N:%.*]]
+; CHECK-NEXT:    ret i64 [[OUT]]
+;
+start:
+  %cmp = icmp ult i64 %x, %n
+  %add = add i64 %x, 1
+  %out = urem i64 %add, %n
+  ret i64 %out
+}
+
+; TODO: https://alive2.llvm.org/ce/z/eHkgRa
+define noundef i8 @urem_with_dominating_condition(i8 %x, i8 %n) {
+; CHECK-LABEL: @urem_with_dominating_condition(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    [[COND:%.*]] = icmp ult i8 [[X:%.*]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[COND]], label [[DOTBB0:%.*]], label [[DOTBB1:%.*]]
+; CHECK:       .bb0:
+; CHECK-NEXT:    [[ADD:%.*]] = add i8 [[X]], 1
+; CHECK-NEXT:    [[OUT:%.*]] = urem i8 [[ADD]], [[N]]
+; CHECK-NEXT:    ret i8 [[OUT]]
+; CHECK:       .bb1:
+; CHECK-NEXT:    ret i8 0
+;
+start:
+  %cond = icmp ult i8 %x, %n
+  br i1 %cond, label %.bb0, label %.bb1 ; Should also works for a dominating condition
+.bb0:
+  %add = add i8 %x, 1
+  %out = urem i8 %add, %n
+  ret i8 %out
+.bb1:
+  ret i8 0
+}
+
+declare void @llvm.assume(i1 noundef)