diff --git a/winsup/cygwin/common.din b/winsup/cygwin/common.din
index a664f1d09..f7c27fd4d 100644
--- a/winsup/cygwin/common.din
+++ b/winsup/cygwin/common.din
@@ -1121,6 +1121,7 @@ pthread_join SIGFE
 pthread_key_create SIGFE
 pthread_key_delete SIGFE
 pthread_kill SIGFE
+pthread_mutex_clocklock SIGFE
 pthread_mutex_destroy SIGFE
 pthread_mutex_getprioceiling SIGFE
 pthread_mutex_init SIGFE
diff --git a/winsup/cygwin/include/pthread.h b/winsup/cygwin/include/pthread.h
index e82a111ce..a55be5d40 100644
--- a/winsup/cygwin/include/pthread.h
+++ b/winsup/cygwin/include/pthread.h
@@ -167,6 +167,10 @@ int pthread_mutex_getprioceiling (const pthread_mutex_t *, int *);
 int pthread_mutex_init (pthread_mutex_t *, const pthread_mutexattr_t *);
 int pthread_mutex_lock (pthread_mutex_t *);
 int pthread_mutex_setprioceiling (pthread_mutex_t *, int, int *);
+#if __GNU_VISIBLE
+int pthread_mutex_clocklock (pthread_mutex_t *, clockid_t,
+			     const struct timespec *);
+#endif
 int pthread_mutex_timedlock (pthread_mutex_t *, const struct timespec *);
 int pthread_mutex_trylock (pthread_mutex_t *);
 int pthread_mutex_unlock (pthread_mutex_t *);
diff --git a/winsup/cygwin/thread.cc b/winsup/cygwin/thread.cc
index 97fcf0c05..55184f8b9 100644
--- a/winsup/cygwin/thread.cc
+++ b/winsup/cygwin/thread.cc
@@ -3475,7 +3475,8 @@ pthread_mutex_lock (pthread_mutex_t *mutex)
 }
 
 extern "C" int
-pthread_mutex_timedlock (pthread_mutex_t *mutex, const struct timespec *abstime)
+pthread_mutex_clocklock (pthread_mutex_t *mutex, clockid_t clock_id,
+			 const struct timespec *abstime)
 {
   LARGE_INTEGER timeout;
 
@@ -3491,7 +3492,7 @@ pthread_mutex_timedlock (pthread_mutex_t *mutex, const struct timespec *abstime)
 
   __try
     {
-      int err = pthread_convert_abstime (CLOCK_REALTIME, abstime, &timeout);
+      int err = pthread_convert_abstime (clock_id, abstime, &timeout);
       if (err)
 	return err;
 
@@ -3502,6 +3503,12 @@ pthread_mutex_timedlock (pthread_mutex_t *mutex, const struct timespec *abstime)
   return EINVAL;
 }
 
+extern "C" int
+pthread_mutex_timedlock (pthread_mutex_t *mutex, const struct timespec *abstime)
+{
+  return pthread_mutex_clocklock (mutex, CLOCK_REALTIME, abstime);
+}
+
 extern "C" int
 pthread_mutex_trylock (pthread_mutex_t *mutex)
 {