Index: llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -4548,6 +4548,20 @@
     }
   }
 
+  // For unsigned predicates / eq / ne:
+  // icmp pred (x << 1), x --> icmp getSignedPredicate(pred) x, 0
+  // icmp pred x, (x << 1) --> icmp getSignedPredicate(pred) 0, x
+  if (!ICmpInst::isSigned(Pred)) {
+    if (BO0 && BO0->getOpcode() == Instruction::Shl &&
+        match(BO0->getOperand(1), m_One()) && Op1 == BO0->getOperand(0))
+      return new ICmpInst(ICmpInst::getSignedPredicate(Pred), Op1,
+                          Constant::getNullValue(Op1->getType()));
+    else if (BO1 && BO1->getOpcode() == Instruction::Shl &&
+             match(BO1->getOperand(1), m_One()) && Op0 == BO1->getOperand(0))
+      return new ICmpInst(ICmpInst::getSignedPredicate(Pred),
+                          Constant::getNullValue(Op0->getType()), Op0);
+  }
+
   if (Value *V = foldMultiplicationOverflowCheck(I))
     return replaceInstUsesWith(I, V);
 
Index: llvm/test/Transforms/InstCombine/icmp-shl-1-overflow.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/InstCombine/icmp-shl-1-overflow.ll
@@ -0,0 +1,241 @@
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+define i1 @icmp_shl_ugt_1(i8 %x) {
+; CHECK-LABEL: @icmp_shl_ugt_1(
+; CHECK-NEXT:    [[R:%.*]] = icmp sgt i8 [[X:%.*]], 0
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %add = shl i8 %x, 1
+  %cmp = icmp ugt i8 %add, %x
+  ret i1 %cmp
+}
+
+define <2 x i1> @icmp_shl_ugt_1_vec(<2 x i8> %x) {
+; CHECK-LABEL: @icmp_shl_ugt_1_vec(
+; CHECK-NEXT:    [[R:%.*]] = icmp sgt <2 x i8> [[X:%.*]], zeroinitializer
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %add = shl <2 x i8> %x, <i8 1, i8 1>
+  %cmp = icmp ugt <2 x i8> %add, %x
+  ret <2 x i1> %cmp
+}
+
+define i1 @icmp_shl_ugt_2(i8 %x) {
+; CHECK-LABEL: @icmp_shl_ugt_2(
+; CHECK-NEXT:    [[R:%.*]] = icmp slt i8 [[X:%.*]], 0
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %add = shl i8 %x, 1
+  %cmp = icmp ugt i8 %x, %add
+  ret i1 %cmp
+}
+
+define <2 x i1> @icmp_shl_ugt_2_vec(<2 x i8> %x) {
+; CHECK-LABEL: @icmp_shl_ugt_2_vec(
+; CHECK-NEXT:    [[R:%.*]] = icmp slt <2 x i8> [[X:%.*]], zeroinitializer
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %add = shl <2 x i8> %x, <i8 1, i8 1>
+  %cmp = icmp ugt <2 x i8> %x, %add
+  ret <2 x i1> %cmp
+}
+
+define i1 @icmp_shl_uge_1(i8 %x) {
+; CHECK-LABEL: @icmp_shl_uge_1(
+; CHECK-NEXT:    [[R:%.*]] = icmp sgt i8 [[X:%.*]], -1
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %add = shl i8 %x, 1
+  %cmp = icmp uge i8 %add, %x
+  ret i1 %cmp
+}
+
+define <2 x i1> @icmp_shl_uge_1_vec(<2 x i8> %x) {
+; CHECK-LABEL: @icmp_shl_uge_1_vec(
+; CHECK-NEXT:    [[R:%.*]] = icmp sgt <2 x i8> [[X:%.*]], <i8 -1, i8 -1>
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %add = shl <2 x i8> %x, <i8 1, i8 1>
+  %cmp = icmp uge <2 x i8> %add, %x
+  ret <2 x i1> %cmp
+}
+
+define i1 @icmp_shl_uge_2(i8 %x) {
+; CHECK-LABEL: @icmp_shl_uge_2(
+; CHECK-NEXT:    [[R:%.*]] = icmp slt i8 [[X:%.*]], 1
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %add = shl i8 %x, 1
+  %cmp = icmp uge i8 %x, %add
+  ret i1 %cmp
+}
+
+define <2 x i1> @icmp_shl_uge_2_vec(<2 x i8> %x) {
+; CHECK-LABEL: @icmp_shl_uge_2_vec(
+; CHECK-NEXT:    [[R:%.*]] = icmp slt <2 x i8> [[X:%.*]], <i8 1, i8 1>
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %add = shl <2 x i8> %x, <i8 1, i8 1>
+  %cmp = icmp uge <2 x i8> %x, %add
+  ret <2 x i1> %cmp
+}
+
+define i1 @icmp_shl_ult_1(i8 %x) {
+; CHECK-LABEL: @icmp_shl_ult_1(
+; CHECK-NEXT:    [[R:%.*]] = icmp slt i8 [[X:%.*]], 0
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %add = shl i8 %x, 1
+  %cmp = icmp ult i8 %add, %x
+  ret i1 %cmp
+}
+
+define <2 x i1> @icmp_shl_ult_1_vec(<2 x i8> %x) {
+; CHECK-LABEL: @icmp_shl_ult_1_vec(
+; CHECK-NEXT:    [[R:%.*]] = icmp slt <2 x i8> [[X:%.*]], zeroinitializer
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %add = shl <2 x i8> %x, <i8 1, i8 1>
+  %cmp = icmp ult <2 x i8> %add, %x
+  ret <2 x i1> %cmp
+}
+
+define i1 @icmp_shl_ult_2(i8 %x) {
+; CHECK-LABEL: @icmp_shl_ult_2(
+; CHECK-NEXT:    [[R:%.*]] = icmp sgt i8 [[X:%.*]], 0
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %add = shl i8 %x, 1
+  %cmp = icmp ult i8 %x, %add
+  ret i1 %cmp
+}
+
+define <2 x i1> @icmp_shl_ult_2_vec(<2 x i8> %x) {
+; CHECK-LABEL: @icmp_shl_ult_2_vec(
+; CHECK-NEXT:    [[R:%.*]] = icmp sgt <2 x i8> [[X:%.*]], zeroinitializer
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %add = shl <2 x i8> %x, <i8 1, i8 1>
+  %cmp = icmp ult <2 x i8> %x, %add
+  ret <2 x i1> %cmp
+}
+
+define i1 @icmp_shl_ule_1(i8 %x) {
+; CHECK-LABEL: @icmp_shl_ule_1(
+; CHECK-NEXT:    [[R:%.*]] = icmp slt i8 [[X:%.*]], 1
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %add = shl i8 %x, 1
+  %cmp = icmp ule i8 %add, %x
+  ret i1 %cmp
+}
+
+define <2 x i1> @icmp_shl_ule_1_vec(<2 x i8> %x) {
+; CHECK-LABEL: @icmp_shl_ule_1_vec(
+; CHECK-NEXT:    [[R:%.*]] = icmp slt <2 x i8> [[X:%.*]], <i8 1, i8 1>
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %add = shl <2 x i8> %x, <i8 1, i8 1>
+  %cmp = icmp ule <2 x i8> %add, %x
+  ret <2 x i1> %cmp
+}
+
+define i1 @icmp_shl_ule_2(i8 %x) {
+; CHECK-LABEL: @icmp_shl_ule_2(
+; CHECK-NEXT:    [[R:%.*]] = icmp sgt i8 [[X:%.*]], -1
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %add = shl i8 %x, 1
+  %cmp = icmp ule i8 %x, %add
+  ret i1 %cmp
+}
+
+define <2 x i1> @icmp_shl_ule_2_vec(<2 x i8> %x) {
+; CHECK-LABEL: @icmp_shl_ule_2_vec(
+; CHECK-NEXT:    [[R:%.*]] = icmp sgt <2 x i8> [[X:%.*]], <i8 -1, i8 -1>
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %add = shl <2 x i8> %x, <i8 1, i8 1>
+  %cmp = icmp ule <2 x i8> %x, %add
+  ret <2 x i1> %cmp
+}
+
+define i1 @icmp_shl_eq_1(i8 %x) {
+; CHECK-LABEL: @icmp_shl_eq_1(
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[X:%.*]], 0
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %add = shl i8 %x, 1
+  %cmp = icmp eq i8 %add, %x
+  ret i1 %cmp
+}
+
+define <2 x i1> @icmp_shl_eq_1_vec(<2 x i8> %x) {
+; CHECK-LABEL: @icmp_shl_eq_1_vec(
+; CHECK-NEXT:    [[R:%.*]] = icmp eq <2 x i8> [[X:%.*]], zeroinitializer
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %add = shl <2 x i8> %x, <i8 1, i8 1>
+  %cmp = icmp eq <2 x i8> %add, %x
+  ret <2 x i1> %cmp
+}
+
+define i1 @icmp_shl_eq_2(i8 %x) {
+; CHECK-LABEL: @icmp_shl_eq_2(
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[X:%.*]], 0
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %add = shl i8 %x, 1
+  %cmp = icmp eq i8 %x, %add
+  ret i1 %cmp
+}
+
+define <2 x i1> @icmp_shl_eq_2_vec(<2 x i8> %x) {
+; CHECK-LABEL: @icmp_shl_eq_2_vec(
+; CHECK-NEXT:    [[R:%.*]] = icmp eq <2 x i8> [[X:%.*]], zeroinitializer
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %add = shl <2 x i8> %x, <i8 1, i8 1>
+  %cmp = icmp eq <2 x i8> %x, %add
+  ret <2 x i1> %cmp
+}
+
+define i1 @icmp_shl_ne_1(i8 %x) {
+; CHECK-LABEL: @icmp_shl_ne_1(
+; CHECK-NEXT:    [[R:%.*]] = icmp ne i8 [[X:%.*]], 0
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %add = shl i8 %x, 1
+  %cmp = icmp ne i8 %add, %x
+  ret i1 %cmp
+}
+
+define <2 x i1> @icmp_shl_ne_1_vec(<2 x i8> %x) {
+; CHECK-LABEL: @icmp_shl_ne_1_vec(
+; CHECK-NEXT:    [[R:%.*]] = icmp ne <2 x i8> [[X:%.*]], zeroinitializer
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %add = shl <2 x i8> %x, <i8 1, i8 1>
+  %cmp = icmp ne <2 x i8> %add, %x
+  ret <2 x i1> %cmp
+}
+
+define i1 @icmp_shl_ne_2(i8 %x) {
+; CHECK-LABEL: @icmp_shl_ne_2(
+; CHECK-NEXT:    [[R:%.*]] = icmp ne i8 [[X:%.*]], 0
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %add = shl i8 %x, 1
+  %cmp = icmp ne i8 %x, %add
+  ret i1 %cmp
+}
+
+define <2 x i1> @icmp_shl_ne_2_vec(<2 x i8> %x) {
+; CHECK-LABEL: @icmp_shl_ne_2_vec(
+; CHECK-NEXT:    [[R:%.*]] = icmp ne <2 x i8> [[X:%.*]], zeroinitializer
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %add = shl <2 x i8> %x, <i8 1, i8 1>
+  %cmp = icmp ne <2 x i8> %x, %add
+  ret <2 x i1> %cmp
+}