diff --git a/src/builtins/builtins-temporal.cc b/src/builtins/builtins-temporal.cc
index b106eb0a7a..c7ccbf285f 100644
--- a/src/builtins/builtins-temporal.cc
+++ b/src/builtins/builtins-temporal.cc
@@ -64,8 +64,6 @@ TO_BE_IMPLEMENTED(TemporalPlainTimePrototypeUntil)
 TO_BE_IMPLEMENTED(TemporalPlainTimePrototypeSince)
 /* Temporal #sec-temporal.plaintime.prototype.round */
 TO_BE_IMPLEMENTED(TemporalPlainTimePrototypeRound)
-/* Temporal #sec-temporal.plaintime.prototype.toplaindatetime */
-TO_BE_IMPLEMENTED(TemporalPlainTimePrototypeToPlainDateTime)
 /* Temporal #sec-temporal.plaintime.prototype.tolocalestring */
 TO_BE_IMPLEMENTED(TemporalPlainTimePrototypeToLocaleString)
 /* Temporal #sec-temporal.plaintime.prototype.tostring */
@@ -432,6 +430,7 @@ TEMPORAL_PROTOTYPE_METHOD1(PlainTime, ToZonedDateTime, toZonedDateTime)
 TEMPORAL_METHOD2(PlainTime, Compare)
 TEMPORAL_PROTOTYPE_METHOD1(PlainTime, Equals, equals)
 TEMPORAL_PROTOTYPE_METHOD0(PlainTime, GetISOFields, getISOFields)
+TEMPORAL_PROTOTYPE_METHOD1(PlainTime, ToPlainDateTime, toPlainDateTime)
 TEMPORAL_VALUE_OF(PlainTime)
 TEMPORAL_PROTOTYPE_METHOD0(PlainTime, ToJSON, toJSON)
 
diff --git a/src/objects/js-temporal-objects.cc b/src/objects/js-temporal-objects.cc
index d596456c0c..fb09bf346f 100644
--- a/src/objects/js-temporal-objects.cc
+++ b/src/objects/js-temporal-objects.cc
@@ -9628,6 +9628,36 @@ MaybeHandle<JSTemporalPlainTime> JSTemporalPlainTime::From(
   return temporal::ToTemporalTime(isolate, item_obj, overflow, method_name);
 }
 
+// #sec-temporal.plaintime.prototype.toplaindatetime
+MaybeHandle<JSTemporalPlainDateTime> JSTemporalPlainTime::ToPlainDateTime(
+    Isolate* isolate, Handle<JSTemporalPlainTime> temporal_time,
+    Handle<Object> temporal_date_like) {
+  // 1. Let temporalTime be the this value.
+  // 2. Perform ? RequireInternalSlot(temporalTime,
+  // [[InitializedTemporalTime]]).
+  // 3. Set temporalDate to ? ToTemporalDate(temporalDate).
+  Handle<JSTemporalPlainDate> temporal_date;
+  ASSIGN_RETURN_ON_EXCEPTION(
+      isolate, temporal_date,
+      ToTemporalDate(isolate, temporal_date_like,
+                     "Temporal.PlainTime.prototype.toPlainDateTime"),
+      JSTemporalPlainDateTime);
+  // 4. Return ? CreateTemporalDateTime(temporalDate.[[ISOYear]],
+  // temporalDate.[[ISOMonth]], temporalDate.[[ISODay]],
+  // temporalTime.[[ISOHour]], temporalTime.[[ISOMinute]],
+  // temporalTime.[[ISOSecond]], temporalTime.[[ISOMillisecond]],
+  // temporalTime.[[ISOMicrosecond]], temporalTime.[[ISONanosecond]],
+  // temporalDate.[[Calendar]]).
+  return temporal::CreateTemporalDateTime(
+      isolate,
+      {{temporal_date->iso_year(), temporal_date->iso_month(),
+        temporal_date->iso_day()},
+       {temporal_time->iso_hour(), temporal_time->iso_minute(),
+        temporal_time->iso_second(), temporal_time->iso_millisecond(),
+        temporal_time->iso_microsecond(), temporal_time->iso_nanosecond()}},
+      handle(temporal_date->calendar(), isolate));
+}
+
 // #sec-temporal.plaintime.prototype.getisofields
 MaybeHandle<JSReceiver> JSTemporalPlainTime::GetISOFields(
     Isolate* isolate, Handle<JSTemporalPlainTime> temporal_time) {
diff --git a/src/objects/js-temporal-objects.h b/src/objects/js-temporal-objects.h
index fa5956217c..13dc4c80d3 100644
--- a/src/objects/js-temporal-objects.h
+++ b/src/objects/js-temporal-objects.h
@@ -478,6 +478,11 @@ class JSTemporalPlainTime
   V8_WARN_UNUSED_RESULT static MaybeHandle<JSReceiver> GetISOFields(
       Isolate* isolate, Handle<JSTemporalPlainTime> plain_time);
 
+  // #sec-temporal.plaintime.prototype.toplaindatetime
+  V8_WARN_UNUSED_RESULT static MaybeHandle<JSTemporalPlainDateTime>
+  ToPlainDateTime(Isolate* isolate, Handle<JSTemporalPlainTime> plain_time,
+                  Handle<Object> temporal_date);
+
   // #sec-temporal.now.plaintimeiso
   V8_WARN_UNUSED_RESULT static MaybeHandle<JSTemporalPlainTime> NowISO(
       Isolate* isolate, Handle<Object> temporal_time_zone_like);
diff --git a/test/mjsunit/mjsunit.status b/test/mjsunit/mjsunit.status
index d9cdd0b2e0..da2e59e87c 100644
--- a/test/mjsunit/mjsunit.status
+++ b/test/mjsunit/mjsunit.status
@@ -400,9 +400,6 @@
   # BUG(v8:12561)
   'spread-large-map': [SKIP],
 
-  # BUG(v8:12907)
-  'temporal/plain-date-time-to-plain-time': [SKIP],
-
   # Flaky tests due to GC interferring with optimization.
   'compiler/regress-crbug-1323114': [SKIP],
 }],  # 'gc_stress'
diff --git a/test/test262/test262.status b/test/test262/test262.status
index 82eb1acdb8..b5ec74307e 100644
--- a/test/test262/test262.status
+++ b/test/test262/test262.status
@@ -1121,18 +1121,6 @@
   'built-ins/Temporal/PlainTime/prototype/subtract/subclassing-ignored': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/toLocaleString/branding': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/toLocaleString/return-string': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-plaindatetime': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-with-utc-designator': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-non-integer': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-out-of-range': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-wrong-type': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/basic': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/branding': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/calendar-datefromfields-called-with-options-undefined': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/calendar-fields-iterable': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/calendar-temporal-object': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/infinity-throws-rangeerror': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/toString/branding': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-invalid-string': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-nan': [FAIL],
@@ -1667,7 +1655,6 @@
   'intl402/Temporal/PlainTime/prototype/toLocaleString/options-undefined': [FAIL],
   'intl402/Temporal/PlainTime/prototype/toLocaleString/resolved-time-zone': [FAIL],
   'intl402/Temporal/PlainTime/prototype/toLocaleString/timezone-getoffsetnanosecondsfor-not-callable': [FAIL],
-  'intl402/Temporal/PlainTime/prototype/toPlainDateTime/infinity-throws-rangeerror': [FAIL],
   'intl402/Temporal/PlainYearMonth/compare/infinity-throws-rangeerror': [FAIL],
   'intl402/Temporal/PlainYearMonth/prototype/equals/infinity-throws-rangeerror': [FAIL],
   'intl402/Temporal/PlainYearMonth/prototype/since/infinity-throws-rangeerror': [FAIL],
@@ -1838,7 +1825,6 @@
   'built-ins/Temporal/PlainTime/prototype/subtract/argument-object-invalid': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/subtract/argument-string-fractional-units-rounding-mode': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/subtract/options-ignored': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/year-zero': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/toString/basic': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-auto': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/toString/fractionalseconddigits-number': [FAIL],
@@ -2012,7 +1998,6 @@
   'built-ins/Temporal/PlainDateTime/prototype/withPlainDate/non-compatible-calendars-throw': [FAIL],
   'built-ins/Temporal/PlainDateTime/prototype/with/string-throws': [FAIL],
   'built-ins/Temporal/PlainDateTime/prototype/with/timezone-throws': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-string-invalid': [FAIL],
   'built-ins/Temporal/ZonedDateTime/prototype/withPlainDate/argument-string-invalid': [FAIL],
 
   'built-ins/Temporal/Duration/compare/options-wrong-type': [FAIL],
@@ -2268,10 +2253,7 @@
   'built-ins/Temporal/PlainTime/prototype/since/argument-number': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/since/argument-wrong-type': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/since/plaintime-propertybag-no-time-units': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-number': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-number': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-propertybag-calendar-wrong-type': [FAIL],
-  'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/argument-wrong-type': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/toPlainDateTime/limits': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/toZonedDateTime/argument-propertybag-calendar-number': [FAIL],
   'built-ins/Temporal/PlainTime/prototype/until/argument-number': [FAIL],