diff --git a/llvm/test/Transforms/InstCombine/icmp-of-trunc-ext.ll b/llvm/test/Transforms/InstCombine/icmp-of-trunc-ext.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/icmp-of-trunc-ext.ll
@@ -0,0 +1,120 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -passes=instcombine < %s | FileCheck %s
+
+declare void @llvm.assume(i1)
+declare void @use(i16)
+define i1 @icmp_trunc_x_trunc_y(i32 %x, i32 %y) {
+; CHECK-LABEL: @icmp_trunc_x_trunc_y(
+; CHECK-NEXT:    [[X_LB_ONLY:%.*]] = icmp ult i32 [[X:%.*]], 65536
+; CHECK-NEXT:    [[Y_LB_ONLY:%.*]] = icmp ult i32 [[Y:%.*]], 65536
+; CHECK-NEXT:    call void @llvm.assume(i1 [[X_LB_ONLY]])
+; CHECK-NEXT:    call void @llvm.assume(i1 [[Y_LB_ONLY]])
+; CHECK-NEXT:    [[X16:%.*]] = trunc i32 [[X]] to i16
+; CHECK-NEXT:    [[Y16:%.*]] = trunc i32 [[Y]] to i16
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i16 [[X16]], [[Y16]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %x_lb_only = icmp ult i32 %x, 65536
+  %y_lb_only = icmp ult i32 %y, 65536
+  call void @llvm.assume(i1 %x_lb_only)
+  call void @llvm.assume(i1 %y_lb_only)
+  %x16 = trunc i32 %x to i16
+  %y16 = trunc i32 %y to i16
+  %r = icmp eq i16 %x16, %y16
+  ret i1 %r
+}
+
+define i1 @icmp_trunc_x_trunc_y_2(i32 %x, i64 %y) {
+; CHECK-LABEL: @icmp_trunc_x_trunc_y_2(
+; CHECK-NEXT:    [[X_LB_ONLY:%.*]] = icmp ult i32 [[X:%.*]], 12345
+; CHECK-NEXT:    [[Y_LB_ONLY:%.*]] = icmp ult i64 [[Y:%.*]], 65536
+; CHECK-NEXT:    call void @llvm.assume(i1 [[X_LB_ONLY]])
+; CHECK-NEXT:    call void @llvm.assume(i1 [[Y_LB_ONLY]])
+; CHECK-NEXT:    [[X16:%.*]] = trunc i32 [[X]] to i16
+; CHECK-NEXT:    [[Y16:%.*]] = trunc i64 [[Y]] to i16
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i16 [[Y16]], [[X16]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %x_lb_only = icmp ult i32 %x, 12345
+  %y_lb_only = icmp ult i64 %y, 65536
+  call void @llvm.assume(i1 %x_lb_only)
+  call void @llvm.assume(i1 %y_lb_only)
+  %x16 = trunc i32 %x to i16
+  %y16 = trunc i64 %y to i16
+  %r = icmp eq i16 %y16, %x16
+  ret i1 %r
+}
+
+define i1 @icmp_trunc_x_trunc_y_fail_maybe_dirty_upper(i32 %x, i32 %y) {
+; CHECK-LABEL: @icmp_trunc_x_trunc_y_fail_maybe_dirty_upper(
+; CHECK-NEXT:    [[X_LB_ONLY:%.*]] = icmp ult i32 [[X:%.*]], 65536
+; CHECK-NEXT:    [[Y_LB_ONLY:%.*]] = icmp ult i32 [[Y:%.*]], 65537
+; CHECK-NEXT:    call void @llvm.assume(i1 [[X_LB_ONLY]])
+; CHECK-NEXT:    call void @llvm.assume(i1 [[Y_LB_ONLY]])
+; CHECK-NEXT:    [[X16:%.*]] = trunc i32 [[X]] to i16
+; CHECK-NEXT:    [[Y16:%.*]] = trunc i32 [[Y]] to i16
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i16 [[X16]], [[Y16]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %x_lb_only = icmp ult i32 %x, 65536
+  %y_lb_only = icmp ult i32 %y, 65537
+  call void @llvm.assume(i1 %x_lb_only)
+  call void @llvm.assume(i1 %y_lb_only)
+  %x16 = trunc i32 %x to i16
+  %y16 = trunc i32 %y to i16
+  %r = icmp eq i16 %x16, %y16
+  ret i1 %r
+}
+
+define i1 @icmp_trunc_x_zext_y(i32 %x, i8 %y) {
+; CHECK-LABEL: @icmp_trunc_x_zext_y(
+; CHECK-NEXT:    [[X_LB_ONLY:%.*]] = icmp ult i32 [[X:%.*]], 65536
+; CHECK-NEXT:    call void @llvm.assume(i1 [[X_LB_ONLY]])
+; CHECK-NEXT:    [[X16:%.*]] = trunc i32 [[X]] to i16
+; CHECK-NEXT:    [[Y16:%.*]] = zext i8 [[Y:%.*]] to i16
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i16 [[X16]], [[Y16]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %x_lb_only = icmp ult i32 %x, 65536
+  call void @llvm.assume(i1 %x_lb_only)
+  %x16 = trunc i32 %x to i16
+  %y16 = zext i8 %y to i16
+  %r = icmp eq i16 %x16, %y16
+  ret i1 %r
+}
+
+define i1 @icmp_trunc_x_zext_y_2(i64 %x, i8 %y) {
+; CHECK-LABEL: @icmp_trunc_x_zext_y_2(
+; CHECK-NEXT:    [[X_LB_ONLY:%.*]] = icmp ult i64 [[X:%.*]], 65536
+; CHECK-NEXT:    call void @llvm.assume(i1 [[X_LB_ONLY]])
+; CHECK-NEXT:    [[X16:%.*]] = trunc i64 [[X]] to i16
+; CHECK-NEXT:    [[Y16:%.*]] = zext i8 [[Y:%.*]] to i16
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i16 [[Y16]], [[X16]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %x_lb_only = icmp ult i64 %x, 65536
+  call void @llvm.assume(i1 %x_lb_only)
+  %x16 = trunc i64 %x to i16
+  %y16 = zext i8 %y to i16
+  %r = icmp eq i16 %y16, %x16
+  ret i1 %r
+}
+
+define i1 @icmp_trunc_x_zext_y_fail_multiuse(i32 %x, i8 %y) {
+; CHECK-LABEL: @icmp_trunc_x_zext_y_fail_multiuse(
+; CHECK-NEXT:    [[X_LB_ONLY:%.*]] = icmp ult i32 [[X:%.*]], 65536
+; CHECK-NEXT:    call void @llvm.assume(i1 [[X_LB_ONLY]])
+; CHECK-NEXT:    [[X16:%.*]] = trunc i32 [[X]] to i16
+; CHECK-NEXT:    [[Y16:%.*]] = zext i8 [[Y:%.*]] to i16
+; CHECK-NEXT:    call void @use(i16 [[Y16]])
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i16 [[X16]], [[Y16]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %x_lb_only = icmp ult i32 %x, 65536
+  call void @llvm.assume(i1 %x_lb_only)
+  %x16 = trunc i32 %x to i16
+  %y16 = zext i8 %y to i16
+  call void @use(i16 %y16)
+  %r = icmp eq i16 %x16, %y16
+  ret i1 %r
+}