diff --git a/Libraries/LibJS/Runtime/Temporal/PlainTimePrototype.cpp b/Libraries/LibJS/Runtime/Temporal/PlainTimePrototype.cpp
index 1eb43e8bcd6..ad4facd86d7 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainTimePrototype.cpp
+++ b/Libraries/LibJS/Runtime/Temporal/PlainTimePrototype.cpp
@@ -38,6 +38,7 @@ void PlainTimePrototype::initialize(Realm& realm)
     u8 attr = Attribute::Writable | Attribute::Configurable;
     define_native_function(realm, vm.names.add, add, 1, attr);
     define_native_function(realm, vm.names.subtract, subtract, 1, attr);
+    define_native_function(realm, vm.names.with, with, 1, attr);
     define_native_function(realm, vm.names.until, until, 1, attr);
     define_native_function(realm, vm.names.since, since, 1, attr);
     define_native_function(realm, vm.names.toString, to_string, 0, attr);
@@ -98,6 +99,72 @@ JS_DEFINE_NATIVE_FUNCTION(PlainTimePrototype::subtract)
     return TRY(add_duration_to_time(vm, ArithmeticOperation::Subtract, temporal_time, temporal_duration_like));
 }
 
+// 4.3.11 Temporal.PlainTime.prototype.with ( temporalTimeLike [ , options ] ), https://tc39.es/proposal-temporal/#sec-temporal.plaintime.prototype.with
+JS_DEFINE_NATIVE_FUNCTION(PlainTimePrototype::with)
+{
+    auto temporal_time_like = vm.argument(0);
+    auto options = vm.argument(1);
+
+    // 1. Let temporalTime be the this value.
+    // 2. Perform ? RequireInternalSlot(temporalTime, [[InitializedTemporalTime]]).
+    auto temporal_time = TRY(typed_this_object(vm));
+
+    // 3. If ? IsPartialTemporalObject(temporalTimeLike) is false, throw a TypeError exception.
+    if (!TRY(is_partial_temporal_object(vm, temporal_time_like)))
+        return vm.throw_completion<TypeError>(ErrorType::TemporalObjectMustBePartialTemporalObject);
+
+    // 4. Let partialTime be ? ToTemporalTimeRecord(temporalTimeLike, PARTIAL).
+    auto partial_time = TRY(to_temporal_time_record(vm, temporal_time_like.as_object(), Completeness::Partial));
+
+    // 5. If partialTime.[[Hour]] is not undefined, then
+    //     a. Let hour be partialTime.[[Hour]].
+    // 6. Else,
+    //     a. Let hour be temporalTime.[[Time]].[[Hour]].
+    auto hour = partial_time.hour.value_or(temporal_time->time().hour);
+
+    // 7. If partialTime.[[Minute]] is not undefined, then
+    //     a. Let minute be partialTime.[[Minute]].
+    // 8. Else,
+    //     a. Let minute be temporalTime.[[Time]].[[Minute]].
+    auto minute = partial_time.minute.value_or(temporal_time->time().minute);
+
+    // 9. If partialTime.[[Second]] is not undefined, then
+    //     a. Let second be partialTime.[[Second]].
+    // 10. Else,
+    //     a. Let second be temporalTime.[[Time]].[[Second]].
+    auto second = partial_time.second.value_or(temporal_time->time().second);
+
+    // 11. If partialTime.[[Millisecond]] is not undefined, then
+    //     a. Let millisecond be partialTime.[[Millisecond]].
+    // 12. Else,
+    //     a. Let millisecond be temporalTime.[[Time]].[[Millisecond]].
+    auto millisecond = partial_time.millisecond.value_or(temporal_time->time().millisecond);
+
+    // 13. If partialTime.[[Microsecond]] is not undefined, then
+    //     a. Let microsecond be partialTime.[[Microsecond]].
+    // 14. Else,
+    //     a. Let microsecond be temporalTime.[[Time]].[[Microsecond]].
+    auto microsecond = partial_time.microsecond.value_or(temporal_time->time().microsecond);
+
+    // 15. If partialTime.[[Nanosecond]] is not undefined, then
+    //     a. Let nanosecond be partialTime.[[Nanosecond]].
+    // 16. Else,
+    //     a. Let nanosecond be temporalTime.[[Time]].[[Nanosecond]].
+    auto nanosecond = partial_time.nanosecond.value_or(temporal_time->time().nanosecond);
+
+    // 17. Let resolvedOptions be ? GetOptionsObject(options).
+    auto resolved_options = TRY(get_options_object(vm, options));
+
+    // 18. Let overflow be ? GetTemporalOverflowOption(resolvedOptions).
+    auto overflow = TRY(get_temporal_overflow_option(vm, resolved_options));
+
+    // 19. Let result be ? RegulateTime(hour, minute, second, millisecond, microsecond, nanosecond, overflow).
+    auto result = TRY(regulate_time(vm, hour, minute, second, millisecond, microsecond, nanosecond, overflow));
+
+    // 20. Return ! CreateTemporalTime(result).
+    return MUST(create_temporal_time(vm, result));
+}
+
 // 4.3.12 Temporal.PlainTime.prototype.until ( other [ , options ] ), https://tc39.es/proposal-temporal/#sec-temporal.plaintime.prototype.until
 JS_DEFINE_NATIVE_FUNCTION(PlainTimePrototype::until)
 {
diff --git a/Libraries/LibJS/Runtime/Temporal/PlainTimePrototype.h b/Libraries/LibJS/Runtime/Temporal/PlainTimePrototype.h
index 8f7492ec277..ae2c19d525a 100644
--- a/Libraries/LibJS/Runtime/Temporal/PlainTimePrototype.h
+++ b/Libraries/LibJS/Runtime/Temporal/PlainTimePrototype.h
@@ -31,6 +31,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(nanosecond_getter);
     JS_DECLARE_NATIVE_FUNCTION(add);
     JS_DECLARE_NATIVE_FUNCTION(subtract);
+    JS_DECLARE_NATIVE_FUNCTION(with);
     JS_DECLARE_NATIVE_FUNCTION(until);
     JS_DECLARE_NATIVE_FUNCTION(since);
     JS_DECLARE_NATIVE_FUNCTION(to_string);
diff --git a/Libraries/LibJS/Tests/builtins/Temporal/PlainTime/PlainTime.prototype.with.js b/Libraries/LibJS/Tests/builtins/Temporal/PlainTime/PlainTime.prototype.with.js
new file mode 100644
index 00000000000..0856941899e
--- /dev/null
+++ b/Libraries/LibJS/Tests/builtins/Temporal/PlainTime/PlainTime.prototype.with.js
@@ -0,0 +1,203 @@
+const PLAIN_TIME_PROPERTIES = [
+    "hour",
+    "minute",
+    "second",
+    "millisecond",
+    "microsecond",
+    "nanosecond",
+];
+
+const REJECTED_CALENDAR_TYPES_THREE_ARGUMENTS = [
+    Temporal.PlainDate,
+    // Temporal.PlainDateTime,
+    Temporal.PlainTime,
+];
+
+const REJECTED_CALENDAR_TYPES_TWO_ARGUMENTS = [Temporal.PlainMonthDay, Temporal.PlainYearMonth];
+
+describe("correct behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.PlainTime.prototype.with).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        const plainTime = new Temporal.PlainTime(1, 2, 3).with({ hour: 4, foo: 5, second: 6 });
+        expect(plainTime.hour).toBe(4);
+        expect(plainTime.minute).toBe(2);
+        expect(plainTime.second).toBe(6);
+    });
+
+    test("each property is looked up from the object", () => {
+        for (const property of PLAIN_TIME_PROPERTIES) {
+            const plainTime = new Temporal.PlainTime().with({ [property]: 1 });
+            expect(plainTime[property]).toBe(1);
+        }
+    });
+
+    test("each property is coerced to number", () => {
+        for (const property of PLAIN_TIME_PROPERTIES) {
+            const plainTime = new Temporal.PlainTime().with({ [property]: "1" });
+            expect(plainTime[property]).toBe(1);
+        }
+    });
+
+    test("argument can have a calendar property as long as it's undefined", () => {
+        expect(() => {
+            new Temporal.PlainTime().with({
+                calendar: undefined,
+            });
+        }).not.toThrowWithMessage(TypeError, "Object must be a partial Temporal object");
+    });
+
+    test("argument can have a timeZone property as long as it's undefined", () => {
+        expect(() => {
+            new Temporal.PlainTime().with({
+                timeZone: undefined,
+            });
+        }).not.toThrowWithMessage(TypeError, "Object must be a partial Temporal object");
+    });
+});
+
+describe("errors", () => {
+    test("this value must be a Temporal.PlainTime object", () => {
+        expect(() => {
+            Temporal.PlainTime.prototype.with.call("foo");
+        }).toThrowWithMessage(TypeError, "Not an object of type Temporal.PlainTime");
+    });
+
+    test("argument is not an object", () => {
+        expect(() => {
+            new Temporal.PlainTime().with("foo");
+        }).toThrowWithMessage(TypeError, "Object must be a partial Temporal object");
+        expect(() => {
+            new Temporal.PlainTime().with(42);
+        }).toThrowWithMessage(TypeError, "Object must be a partial Temporal object");
+    });
+
+    test("options is not an object", () => {
+        expect(() => {
+            new Temporal.PlainTime().with({ hour: 1 }, "foo");
+        }).toThrowWithMessage(TypeError, "Options is not an object");
+        expect(() => {
+            new Temporal.PlainTime().with({ hour: 1 }, 42);
+        }).toThrowWithMessage(TypeError, "Options is not an object");
+    });
+
+    test("invalid overflow option", () => {
+        expect(() => {
+            new Temporal.PlainTime().with({ hour: 1 }, { overflow: "a" });
+        }).toThrowWithMessage(RangeError, "a is not a valid value for option overflow");
+    });
+
+    test("argument is an invalid plain time-like object", () => {
+        expect(() => {
+            new Temporal.PlainTime().with({});
+        }).toThrowWithMessage(TypeError, "Invalid time");
+        expect(() => {
+            new Temporal.PlainTime().with({ foo: 1, bar: 2 });
+        }).toThrowWithMessage(TypeError, "Invalid time");
+    });
+
+    test("error when coercing property to number", () => {
+        for (const property of PLAIN_TIME_PROPERTIES) {
+            expect(() => {
+                new Temporal.PlainTime().with({
+                    [property]: {
+                        valueOf() {
+                            throw new Error("error occurred");
+                        },
+                    },
+                });
+            }).toThrowWithMessage(Error, "error occurred");
+        }
+    });
+
+    test("property must be finite", () => {
+        for (const property of PLAIN_TIME_PROPERTIES) {
+            expect(() => {
+                new Temporal.PlainTime().with({ [property]: Infinity });
+            }).toThrowWithMessage(
+                RangeError,
+                `Invalid value Infinity for time field '${property}'`
+            );
+            expect(() => {
+                new Temporal.PlainTime().with({ [property]: -Infinity });
+            }).toThrowWithMessage(
+                RangeError,
+                `Invalid value -Infinity for time field '${property}'`
+            );
+        }
+    });
+
+    test("error when getting property", () => {
+        for (const property of PLAIN_TIME_PROPERTIES) {
+            expect(() => {
+                new Temporal.PlainTime().with({
+                    get [property]() {
+                        throw new Error("error occurred");
+                    },
+                });
+            }).toThrowWithMessage(Error, "error occurred");
+        }
+    });
+
+    test("argument must not have a defined calendar property", () => {
+        expect(() => {
+            new Temporal.PlainTime().with({
+                calendar: null,
+            });
+        }).toThrowWithMessage(TypeError, "Object must be a partial Temporal object");
+        expect(() => {
+            new Temporal.PlainTime().with({
+                calendar: 1,
+            });
+        }).toThrowWithMessage(TypeError, "Object must be a partial Temporal object");
+    });
+
+    test("argument must not have a defined timeZone property", () => {
+        expect(() => {
+            new Temporal.PlainTime().with({
+                timeZone: null,
+            });
+        }).toThrowWithMessage(TypeError, "Object must be a partial Temporal object");
+        expect(() => {
+            new Temporal.PlainTime().with({
+                timeZone: 1,
+            });
+        }).toThrowWithMessage(TypeError, "Object must be a partial Temporal object");
+    });
+
+    test("error when getting calendar", () => {
+        expect(() => {
+            new Temporal.PlainTime().with({
+                get calendar() {
+                    throw new Error("error occurred");
+                },
+            });
+        }).toThrowWithMessage(Error, "error occurred");
+    });
+
+    test("error when getting timeZone", () => {
+        expect(() => {
+            new Temporal.PlainTime().with({
+                get timeZone() {
+                    throw new Error("error occurred");
+                },
+            });
+        }).toThrowWithMessage(Error, "error occurred");
+    });
+
+    test("rejects calendar types", () => {
+        for (const typeWithCalendar of REJECTED_CALENDAR_TYPES_THREE_ARGUMENTS) {
+            expect(() => {
+                new Temporal.PlainTime().with(new typeWithCalendar(1, 1, 1));
+            }).toThrowWithMessage(TypeError, "Object must be a partial Temporal object");
+        }
+
+        for (const typeWithCalendar of REJECTED_CALENDAR_TYPES_TWO_ARGUMENTS) {
+            expect(() => {
+                new Temporal.PlainTime().with(new typeWithCalendar(1, 1));
+            }).toThrowWithMessage(TypeError, "Object must be a partial Temporal object");
+        }
+    });
+});