diff --git a/JSTests/stress/temporal-plaindatetime.js b/JSTests/stress/temporal-plaindatetime.js
index 6391a13f7ddc5..39fff8c2ccb21 100644
--- a/JSTests/stress/temporal-plaindatetime.js
+++ b/JSTests/stress/temporal-plaindatetime.js
@@ -279,10 +279,6 @@ shouldBe(pdt.with({ second: 15 }).toString(), '0001-02-03T04:05:15.007008009');
 shouldBe(pdt.with({ day: 30 }).toString(), '0001-02-28T04:05:06.007008009');
 shouldThrow(() => { pdt.with({ day: 30 }, { overflow: 'reject' }); }, RangeError);
 
-shouldBe(Temporal.PlainDateTime.prototype.withPlainDate.length, 1);
-shouldThrow(() => { pdt.withPlainDate(); }, TypeError);
-shouldBe(pdt.withPlainDate({ year: 2000, month: 10, day: 30 }).toString(), '2000-10-30T04:05:06.007008009');
-
 shouldBe(Temporal.PlainDateTime.prototype.withPlainTime.length, 0);
 shouldBe(pdt.withPlainTime().toString(), '0001-02-03T00:00:00');
 shouldBe(pdt.withPlainTime({ hour: 1, minute: 2, second: 3 }).toString(), '0001-02-03T01:02:03');
diff --git a/JSTests/stress/temporal-plaintime.js b/JSTests/stress/temporal-plaintime.js
index 71a571178e36c..63daf442d50e0 100644
--- a/JSTests/stress/temporal-plaintime.js
+++ b/JSTests/stress/temporal-plaintime.js
@@ -145,9 +145,6 @@ shouldBe(String(Temporal.PlainTime.from('2007-01-09 03:24:30[u-ca=japanese]')),
     let dateTime = Temporal.PlainDateTime.from('1995-12-07T03:24:30+01:00[Europe/Brussels]')
     shouldBe(Temporal.PlainTime.from(dateTime).toString(), time.toString());
 
-    let date = Temporal.PlainDate.from('1995-12-07T03:24:30+01:00[Europe/Brussels]');
-    shouldBe(time.toPlainDateTime(date).toString(), dateTime.toString());
-
     shouldBe(time.toJSON(), time.toString());
     shouldBe(time.toLocaleString(), time.toString());
 }
diff --git a/Source/JavaScriptCore/runtime/TemporalPlainDateTimePrototype.cpp b/Source/JavaScriptCore/runtime/TemporalPlainDateTimePrototype.cpp
index d6929d7d92a45..53c632844e1b4 100644
--- a/Source/JavaScriptCore/runtime/TemporalPlainDateTimePrototype.cpp
+++ b/Source/JavaScriptCore/runtime/TemporalPlainDateTimePrototype.cpp
@@ -40,7 +40,6 @@ static JSC_DECLARE_HOST_FUNCTION(temporalPlainDateTimePrototypeFuncGetISOFields)
 static JSC_DECLARE_HOST_FUNCTION(temporalPlainDateTimePrototypeFuncAdd);
 static JSC_DECLARE_HOST_FUNCTION(temporalPlainDateTimePrototypeFuncSubtract);
 static JSC_DECLARE_HOST_FUNCTION(temporalPlainDateTimePrototypeFuncWith);
-static JSC_DECLARE_HOST_FUNCTION(temporalPlainDateTimePrototypeFuncWithPlainDate);
 static JSC_DECLARE_HOST_FUNCTION(temporalPlainDateTimePrototypeFuncWithPlainTime);
 static JSC_DECLARE_HOST_FUNCTION(temporalPlainDateTimePrototypeFuncRound);
 static JSC_DECLARE_HOST_FUNCTION(temporalPlainDateTimePrototypeFuncEquals);
@@ -84,7 +83,6 @@ const ClassInfo TemporalPlainDateTimePrototype::s_info = { "Temporal.PlainDateTi
   add              temporalPlainDateTimePrototypeFuncAdd                DontEnum|Function 1
   subtract         temporalPlainDateTimePrototypeFuncSubtract           DontEnum|Function 1
   with             temporalPlainDateTimePrototypeFuncWith               DontEnum|Function 1
-  withPlainDate    temporalPlainDateTimePrototypeFuncWithPlainDate      DontEnum|Function 1
   withPlainTime    temporalPlainDateTimePrototypeFuncWithPlainTime      DontEnum|Function 0
   round            temporalPlainDateTimePrototypeFuncRound              DontEnum|Function 1
   equals           temporalPlainDateTimePrototypeFuncEquals             DontEnum|Function 1
@@ -243,22 +241,6 @@ JSC_DEFINE_HOST_FUNCTION(temporalPlainDateTimePrototypeFuncWith, (JSGlobalObject
     RELEASE_AND_RETURN(scope, JSValue::encode(plainDateTime->with(globalObject, asObject(temporalDateTimeLike), callFrame->argument(1))));
 }
 
-// https://tc39.es/proposal-temporal/#sec-temporal.plaindatetime.prototype.withplaindate
-JSC_DEFINE_HOST_FUNCTION(temporalPlainDateTimePrototypeFuncWithPlainDate, (JSGlobalObject* globalObject, CallFrame* callFrame))
-{
-    VM& vm = globalObject->vm();
-    auto scope = DECLARE_THROW_SCOPE(vm);
-
-    auto* plainDateTime = jsDynamicCast<TemporalPlainDateTime*>(callFrame->thisValue());
-    if (!plainDateTime)
-        return throwVMTypeError(globalObject, scope, "Temporal.PlainDateTime.prototype.withPlainDate called on value that's not a PlainDateTime"_s);
-
-    auto* plainDate = TemporalPlainDate::from(globalObject, callFrame->argument(0), std::nullopt);
-    RETURN_IF_EXCEPTION(scope, { });
-
-    RELEASE_AND_RETURN(scope, JSValue::encode(TemporalPlainDateTime::tryCreateIfValid(globalObject, globalObject->plainDateTimeStructure(), plainDate->plainDate(), plainDateTime->plainTime())));
-}
-
 // https://tc39.es/proposal-temporal/#sec-temporal.plaindatetime.prototype.withplaintime
 JSC_DEFINE_HOST_FUNCTION(temporalPlainDateTimePrototypeFuncWithPlainTime, (JSGlobalObject* globalObject, CallFrame* callFrame))
 {
diff --git a/Source/JavaScriptCore/runtime/TemporalPlainTimePrototype.cpp b/Source/JavaScriptCore/runtime/TemporalPlainTimePrototype.cpp
index 1ad06ddddb321..2e2eb1df98742 100644
--- a/Source/JavaScriptCore/runtime/TemporalPlainTimePrototype.cpp
+++ b/Source/JavaScriptCore/runtime/TemporalPlainTimePrototype.cpp
@@ -43,7 +43,6 @@ static JSC_DECLARE_HOST_FUNCTION(temporalPlainTimePrototypeFuncSince);
 static JSC_DECLARE_HOST_FUNCTION(temporalPlainTimePrototypeFuncRound);
 static JSC_DECLARE_HOST_FUNCTION(temporalPlainTimePrototypeFuncEquals);
 static JSC_DECLARE_HOST_FUNCTION(temporalPlainTimePrototypeFuncGetISOFields);
-static JSC_DECLARE_HOST_FUNCTION(temporalPlainTimePrototypeFuncToPlainDateTime);
 static JSC_DECLARE_HOST_FUNCTION(temporalPlainTimePrototypeFuncToString);
 static JSC_DECLARE_HOST_FUNCTION(temporalPlainTimePrototypeFuncToJSON);
 static JSC_DECLARE_HOST_FUNCTION(temporalPlainTimePrototypeFuncToLocaleString);
@@ -74,7 +73,6 @@ const ClassInfo TemporalPlainTimePrototype::s_info = { "Temporal.PlainTime"_s, &
   round            temporalPlainTimePrototypeFuncRound              DontEnum|Function 1
   equals           temporalPlainTimePrototypeFuncEquals             DontEnum|Function 1
   getISOFields     temporalPlainTimePrototypeFuncGetISOFields       DontEnum|Function 0
-  toPlainDateTime  temporalPlainTimePrototypeFuncToPlainDateTime    DontEnum|Function 1
   toString         temporalPlainTimePrototypeFuncToString           DontEnum|Function 0
   toJSON           temporalPlainTimePrototypeFuncToJSON             DontEnum|Function 0
   toLocaleString   temporalPlainTimePrototypeFuncToLocaleString     DontEnum|Function 0
@@ -266,22 +264,6 @@ JSC_DEFINE_HOST_FUNCTION(temporalPlainTimePrototypeFuncGetISOFields, (JSGlobalOb
     return JSValue::encode(fields);
 }
 
-// https://tc39.es/proposal-temporal/#sec-temporal.plaintime.prototype.toplaindatetime
-JSC_DEFINE_HOST_FUNCTION(temporalPlainTimePrototypeFuncToPlainDateTime, (JSGlobalObject* globalObject, CallFrame* callFrame))
-{
-    VM& vm = globalObject->vm();
-    auto scope = DECLARE_THROW_SCOPE(vm);
-
-    auto* plainTime = jsDynamicCast<TemporalPlainTime*>(callFrame->thisValue());
-    if (!plainTime)
-        return throwVMTypeError(globalObject, scope, "Temporal.PlainTime.prototype.toPlainDateTime called on value that's not a PlainTime"_s);
-
-    auto* plainDate = TemporalPlainDate::from(globalObject, callFrame->argument(0), std::nullopt);
-    RETURN_IF_EXCEPTION(scope, { });
-
-    RELEASE_AND_RETURN(scope, JSValue::encode(TemporalPlainDateTime::tryCreateIfValid(globalObject, globalObject->plainDateTimeStructure(), plainDate->plainDate(), plainTime->plainTime())));
-}
-
 // https://tc39.es/proposal-temporal/#sec-temporal.plaintime.prototype.tostring
 JSC_DEFINE_HOST_FUNCTION(temporalPlainTimePrototypeFuncToString, (JSGlobalObject* globalObject, CallFrame* callFrame))
 {