diff --git a/ChangeLog b/ChangeLog
index 36430d6169..af84374b68 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -6,6 +6,58 @@
 	__libc_cleanup_end): Rewrite implementation using
 	__attribute__ ((__cleanup__)).
 	(__libc_cleanup_push, __libc_cleanup_pop): New macros.
+	* hurd/Makefile (routines): Add hurdlock.
+	* hurd/Versions (GLIBC_PRIVATE): Added new entry to export the above
+	interface.
+	(HURD_CTHREADS_0.3): Remove __libc_getspecific.
+	* hurd/hurdpid.c: Include <lowlevellock.h>
+	(_S_msg_proc_newids): Use lll_wait to synchronize.
+	* hurd/hurdsig.c: (reauth_proc): Use __mutex_lock and __mutex_unlock.
+	* hurd/setauth.c: Include <hurdlock.h>, use integer for synchronization.
+	* mach/Makefile (lock-headers): Remove machine-lock.h.
+	* mach/lock-intern.h: Include <lowlevellock.h> instead of
+	<machine-lock.h>.
+	(__spin_lock_t): New type.
+	(__SPIN_LOCK_INITIALIZER): New macro.
+	(__spin_lock, __spin_unlock, __spin_try_lock, __spin_lock_locked,
+	__mutex_init, __mutex_lock_solid, __mutex_unlock_solid, __mutex_lock,
+	__mutex_unlock, __mutex_trylock): Use lll to implement locks.
+	* mach/mutex-init.c: Include <lowlevellock.h> instead of <cthreads.h>.
+	(__mutex_init): Initialize with lll.
+	* manual/errno.texi (EOWNERDEAD, ENOTRECOVERABLE): New errno values.
+	* sysdeps/mach/Makefile: Add libmachuser as dependencies for libs
+	needing lll.
+	* sysdeps/mach/hurd/bits/errno.h: Regenerate.
+	* sysdeps/mach/hurd/cthreads.c (__libc_getspecific): Remove function.
+	* sysdeps/mach/hurd/bits/libc-lock.h: Remove file.
+	* sysdeps/mach/hurd/setpgid.c: Include <lowlevellock.h>.
+	(__setpgid): Use lll for synchronization.
+	* sysdeps/mach/hurd/setsid.c: Likewise with __setsid.
+	* sysdeps/mach/bits/libc-lock.h: Include <tls.h> and <lowlevellock.h>
+	instead of <cthreads.h>.
+	(_IO_lock_inexpensive): New macro
+	(__libc_lock_recursive_t, __rtld_lock_recursive_t): New structures.
+	(__libc_lock_self0): New declaration.
+	(__libc_lock_owner_self): New macro.
+	(__libc_key_t): Remove type.
+	(_LIBC_LOCK_INITIALIZER): New macro.
+	(__libc_lock_define_initialized, __libc_lock_init, __libc_lock_fini,
+	__libc_lock_fini_recursive, __rtld_lock_fini_recursive,
+	__libc_lock_lock, __libc_lock_trylock, __libc_lock_unlock,
+	__libc_lock_define_initialized_recursive,
+	__rtld_lock_define_initialized_recursive,
+	__libc_lock_init_recursive, __libc_lock_trylock_recursive,
+	__libc_lock_lock_recursive, __libc_lock_unlock_recursive,
+	__rtld_lock_initialize, __rtld_lock_trylock_recursive,
+	__rtld_lock_lock_recursive, __rtld_lock_unlock_recursive
+	__libc_once_define, __libc_mutex_unlock): Reimplement with lll.
+	(__libc_lock_define_recursive, __rtld_lock_define_recursive,
+	_LIBC_LOCK_RECURSIVE_INITIALIZER, _RTLD_LOCK_RECURSIVE_INITIALIZER):
+	New macros.
+	Include <libc-lockP.h> to reimplement libc_key* with pthread_key*.
+	* hurd/hurdlock.c: New file.
+	* hurd/hurdlock.h: New file.
+	* mach/lowlevellock.h: New file
 
 2018-03-18  Samuel Thibault  <samuel.thibault@ens-lyon.org>
 
diff --git a/hurd/Makefile b/hurd/Makefile
index 2b318c9ca0..7a787d2900 100644
--- a/hurd/Makefile
+++ b/hurd/Makefile
@@ -54,6 +54,7 @@ routines = hurdstartup hurdinit \
 	   vpprintf \
 	   ports-get ports-set hurdports hurdmsg \
 	   errno-loc \
+	   hurdlock \
 	   $(sig) $(dtable) $(inlines) port-cleanup report-wait xattr
 sig	= hurdsig hurdfault siginfo hurd-raise preempt-sig \
 	  trampoline longjmp-ts catch-exc exc2signal hurdkill sigunwind \
diff --git a/hurd/Versions b/hurd/Versions
index 602391ca08..af6a0e45de 100644
--- a/hurd/Versions
+++ b/hurd/Versions
@@ -147,6 +147,13 @@ libc {
 
     # cthreads functions with stubs in libc
     __cthread_keycreate; __cthread_getspecific; __cthread_setspecific;
-    __libc_getspecific;
+  }
+
+  GLIBC_PRIVATE {
+    # Used by other libs.
+    __lll_abstimed_wait; __lll_abstimed_xwait;
+    __lll_abstimed_lock; __lll_robust_lock;
+    __lll_robust_abstimed_lock; __lll_robust_trylock;
+    __lll_robust_unlock;
   }
 }
diff --git a/hurd/hurdlock.c b/hurd/hurdlock.c
new file mode 100644
index 0000000000..c06b03cf30
--- /dev/null
+++ b/hurd/hurdlock.c
@@ -0,0 +1,215 @@
+/* Hurd helpers for lowlevellocks.
+   Copyright (C) 1999-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include "hurdlock.h"
+#include <hurd.h>
+#include <hurd/hurd.h>
+#include <time.h>
+#include <errno.h>
+#include <unistd.h>
+
+/* Convert an absolute timeout in nanoseconds to a relative
+   timeout in milliseconds.  */
+static inline int __attribute__ ((gnu_inline))
+compute_reltime (const struct timespec *abstime, clockid_t clk)
+{
+  struct timespec ts;
+  __clock_gettime (clk, &ts);
+
+  ts.tv_sec = abstime->tv_sec - ts.tv_sec;
+  ts.tv_nsec = abstime->tv_nsec - ts.tv_nsec;
+
+  if (ts.tv_nsec < 0)
+    {
+      --ts.tv_sec;
+      ts.tv_nsec += 1000000000;
+    }
+
+  return (ts.tv_sec < 0 ? -1 :
+    (int)(ts.tv_sec * 1000 + ts.tv_nsec / 1000000));
+}
+
+int __lll_abstimed_wait (void *ptr, int val,
+  const struct timespec *tsp, int flags, int clk)
+{
+  int mlsec = compute_reltime (tsp, clk);
+  return (mlsec < 0 ? KERN_TIMEDOUT :
+    lll_timed_wait (ptr, val, mlsec, flags));
+}
+
+int __lll_abstimed_xwait (void *ptr, int lo, int hi,
+  const struct timespec *tsp, int flags, int clk)
+{
+  int mlsec = compute_reltime (tsp, clk);
+  return (mlsec < 0 ? KERN_TIMEDOUT :
+    lll_timed_xwait (ptr, lo, hi, mlsec, flags));
+}
+
+int __lll_abstimed_lock (void *ptr,
+  const struct timespec *tsp, int flags, int clk)
+{
+  if (lll_trylock (ptr) == 0)
+    return (0);
+
+  while (1)
+    {
+      if (atomic_exchange_acq ((int *)ptr, 2) == 0)
+        return (0);
+      else if (tsp->tv_nsec < 0 || tsp->tv_nsec >= 1000000000)
+        return (EINVAL);
+
+      int mlsec = compute_reltime (tsp, clk);
+      if (mlsec < 0 || lll_timed_wait (ptr,
+          2, mlsec, flags) == KERN_TIMEDOUT)
+        return (ETIMEDOUT);
+    }
+}
+
+/* Robust locks.  */
+
+/* Test if a given process id is still valid.  */
+static inline int valid_pid (int pid)
+{
+  task_t task = __pid2task (pid);
+  if (task == MACH_PORT_NULL)
+    return (0);
+
+  __mach_port_deallocate (__mach_task_self (), task);
+  return (1);
+}
+
+/* Robust locks have currently no support from the kernel; they
+   are simply implemented with periodic polling. When sleeping, the
+   maximum blocking time is determined by this constant.  */
+#define MAX_WAIT_TIME   1500
+
+int __lll_robust_lock (void *ptr, int flags)
+{
+  int *iptr = (int *)ptr;
+  int id = __getpid ();
+  int wait_time = 25;
+  unsigned int val;
+
+  /* Try to set the lock word to our PID if it's clear. Otherwise,
+     mark it as having waiters.  */
+  while (1)
+    {
+      val = *iptr;
+      if (!val && atomic_compare_and_exchange_bool_acq (iptr, id, 0) == 0)
+        return (0);
+      else if (atomic_compare_and_exchange_bool_acq (iptr,
+          val | LLL_WAITERS, val) == 0)
+        break;
+    }
+
+  for (id |= LLL_WAITERS ; ; )
+    {
+      val = *iptr;
+      if (!val && atomic_compare_and_exchange_bool_acq (iptr, id, 0) == 0)
+        return (0);
+      else if (val && !valid_pid (val & LLL_OWNER_MASK))
+        {
+          if (atomic_compare_and_exchange_bool_acq (iptr, id, val) == 0)
+            return (EOWNERDEAD);
+        }
+      else
+        {
+          lll_timed_wait (iptr, val, wait_time, flags);
+          if (wait_time < MAX_WAIT_TIME)
+            wait_time <<= 1;
+        }
+    }
+}
+
+int __lll_robust_abstimed_lock (void *ptr,
+  const struct timespec *tsp, int flags, int clk)
+{
+  int *iptr = (int *)ptr;
+  int id = __getpid ();
+  int wait_time = 25;
+  unsigned int val;
+
+  while (1)
+    {
+      val = *iptr;
+      if (!val && atomic_compare_and_exchange_bool_acq (iptr, id, 0) == 0)
+        return (0);
+      else if (atomic_compare_and_exchange_bool_acq (iptr,
+          val | LLL_WAITERS, val) == 0)
+        break;
+    }
+
+  for (id |= LLL_WAITERS ; ; )
+    {
+      val = *iptr;
+      if (!val && atomic_compare_and_exchange_bool_acq (iptr, id, 0) == 0)
+        return (0);
+      else if (val && !valid_pid (val & LLL_OWNER_MASK))
+        {
+          if (atomic_compare_and_exchange_bool_acq (iptr, id, val) == 0)
+            return (EOWNERDEAD);
+        }
+      else
+        {
+          int mlsec = compute_reltime (tsp, clk);
+          if (mlsec < 0)
+            return (ETIMEDOUT);
+          else if (mlsec > wait_time)
+            mlsec = wait_time;
+
+          int res = lll_timed_wait (iptr, val, mlsec, flags);
+          if (res == KERN_TIMEDOUT)
+            return (ETIMEDOUT);
+          else if (wait_time < MAX_WAIT_TIME)
+            wait_time <<= 1;
+        }
+    }
+}
+
+int __lll_robust_trylock (void *ptr)
+{
+  int *iptr = (int *)ptr;
+  int id = __getpid ();
+  unsigned int val = *iptr;
+
+  if (!val)
+    {
+      if (atomic_compare_and_exchange_bool_acq (iptr, id, 0) == 0)
+        return (0);
+    }
+  else if (!valid_pid (val & LLL_OWNER_MASK) &&
+      atomic_compare_and_exchange_bool_acq (iptr, id, val) == 0)
+    return (EOWNERDEAD);
+
+  return (EBUSY);
+}
+
+void __lll_robust_unlock (void *ptr, int flags)
+{
+  unsigned int val = atomic_load_relaxed((unsigned int *)ptr);
+  while (1)
+    {
+      if (val & LLL_WAITERS)
+        {
+          lll_set_wake (ptr, 0, flags);
+          break;
+        }
+      else if (atomic_compare_exchange_weak_release ((unsigned int *)ptr, &val, 0))
+        break;
+    }
+}
diff --git a/hurd/hurdlock.h b/hurd/hurdlock.h
new file mode 100644
index 0000000000..af57e25387
--- /dev/null
+++ b/hurd/hurdlock.h
@@ -0,0 +1,125 @@
+/* Low-level lock implementation.  High-level Hurd helpers.
+   Copyright (C) 1999-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _HURD_LOCK_H
+#define _HURD_LOCK_H   1
+
+#include <mach/lowlevellock.h>
+
+struct timespec;
+
+/* Flags for robust locks.  */
+#define LLL_WAITERS      (1U << 31)
+#define LLL_DEAD_OWNER   (1U << 30)
+
+#define LLL_OWNER_MASK   ~(LLL_WAITERS | LLL_DEAD_OWNER)
+
+/* Wait on 64-bit address PTR, without blocking if its contents
+   are different from the pair <LO, HI>.  */
+#define lll_xwait(ptr, lo, hi, flags) \
+  __gsync_wait (__mach_task_self (), \
+    (vm_offset_t)ptr, lo, hi, 0, flags | GSYNC_QUAD)
+
+/* Same as 'lll_wait', but only block for MLSEC milliseconds.  */
+#define lll_timed_wait(ptr, val, mlsec, flags) \
+  __gsync_wait (__mach_task_self (), \
+    (vm_offset_t)ptr, val, 0, mlsec, flags | GSYNC_TIMED)
+
+/* Same as 'lll_xwait', but only block for MLSEC milliseconds.  */
+#define lll_timed_xwait(ptr, lo, hi, mlsec, flags) \
+  __gsync_wait (__mach_task_self (), (vm_offset_t)ptr, \
+    lo, hi, mlsec, flags | GSYNC_TIMED | GSYNC_QUAD)
+
+/* Same as 'lll_wait', but only block until TSP elapses,
+   using clock CLK.  */
+extern int __lll_abstimed_wait (void *__ptr, int __val,
+  const struct timespec *__tsp, int __flags, int __clk);
+
+/* Same as 'lll_xwait', but only block until TSP elapses,
+   using clock CLK.  */
+extern int __lll_abstimed_xwait (void *__ptr, int __lo, int __hi,
+  const struct timespec *__tsp, int __flags, int __clk);
+
+/* Same as 'lll_lock', but return with an error if TSP elapses,
+   using clock CLK.  */
+extern int __lll_abstimed_lock (void *__ptr,
+  const struct timespec *__tsp, int __flags, int __clk);
+
+/* Acquire the lock at PTR, but return with an error if
+   the process containing the owner thread dies.  */
+extern int __lll_robust_lock (void *__ptr, int __flags);
+
+/* Same as '__lll_robust_lock', but only block until TSP
+   elapses, using clock CLK.  */
+extern int __lll_robust_abstimed_lock (void *__ptr,
+  const struct timespec *__tsp, int __flags, int __clk);
+
+/* Same as '__lll_robust_lock', but return with an error
+   if the lock cannot be acquired without blocking.  */
+extern int __lll_robust_trylock (void *__ptr);
+
+/* Wake one or more threads waiting on address PTR,
+   setting its value to VAL before doing so.  */
+#define lll_set_wake(ptr, val, flags) \
+  __gsync_wake (__mach_task_self (), \
+    (vm_offset_t)ptr, val, flags | GSYNC_MUTATE)
+
+/* Release the robust lock at PTR.  */
+extern void __lll_robust_unlock (void *__ptr, int __flags);
+
+/* Rearrange threads waiting on address SRC to instead wait on
+   DST, waking one of them if WAIT_ONE is non-zero.  */
+#define lll_requeue(src, dst, wake_one, flags) \
+  __gsync_requeue (__mach_task_self (), (vm_offset_t)src, \
+    (vm_offset_t)dst, (boolean_t)wake_one, flags)
+
+/* The following are hacks that allow us to simulate optional
+   parameters in C, to avoid having to pass the clock id for
+   every one of these calls, defaulting to CLOCK_REALTIME if
+   no argument is passed.  */
+
+#define lll_abstimed_wait(ptr, val, tsp, flags, ...)   \
+  ({   \
+     const clockid_t __clk[] = { CLOCK_REALTIME, ##__VA_ARGS__ };   \
+     __lll_abstimed_wait ((ptr), (val), (tsp), (flags),   \
+       __clk[sizeof (__clk) / sizeof (__clk[0]) - 1]);   \
+   })
+
+#define lll_abstimed_xwait(ptr, lo, hi, tsp, flags, ...)   \
+  ({   \
+     const clockid_t __clk[] = { CLOCK_REALTIME, ##__VA_ARGS__ };   \
+     __lll_abstimed_xwait ((ptr), (lo), (hi), (tsp), (flags),   \
+       __clk[sizeof (__clk) / sizeof (__clk[0]) - 1]);   \
+   })
+
+#define lll_abstimed_lock(ptr, tsp, flags, ...)   \
+  ({   \
+     const clockid_t __clk[] = { CLOCK_REALTIME, ##__VA_ARGS__ };   \
+     __lll_abstimed_lock ((ptr), (tsp), (flags),   \
+       __clk[sizeof (__clk) / sizeof (__clk[0]) - 1]);   \
+   })
+
+#define lll_robust_abstimed_lock(ptr, tsp, flags, ...)   \
+  ({   \
+     const clockid_t __clk[] = { CLOCK_REALTIME, ##__VA_ARGS__ };   \
+     __lll_robust_abstimed_lock ((ptr), (tsp), (flags),   \
+       __clk[sizeof (__clk) / sizeof (__clk[0]) - 1]);   \
+   })
+
+
+#endif
diff --git a/hurd/hurdpid.c b/hurd/hurdpid.c
index e1dd09316d..33659cc1ba 100644
--- a/hurd/hurdpid.c
+++ b/hurd/hurdpid.c
@@ -16,6 +16,8 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <hurd.h>
+#include <lowlevellock.h>
+
 pid_t _hurd_pid, _hurd_ppid, _hurd_pgrp;
 int _hurd_orphaned;
 
@@ -66,6 +68,7 @@ _S_msg_proc_newids (mach_port_t me,
 
   /* Notify any waiting user threads that the id change as been completed.  */
   ++_hurd_pids_changed_stamp;
+  lll_wake (&_hurd_pids_changed_stamp, GSYNC_BROADCAST);
 
   return 0;
 }
diff --git a/hurd/hurdsig.c b/hurd/hurdsig.c
index ea76be7e32..fdadd5b694 100644
--- a/hurd/hurdsig.c
+++ b/hurd/hurdsig.c
@@ -1362,14 +1362,14 @@ reauth_proc (mach_port_t new)
   __mach_port_destroy (__mach_task_self (), ref);
 
   /* Set the owner of the process here too. */
-  mutex_lock (&_hurd_id.lock);
+  __mutex_lock (&_hurd_id.lock);
   if (!_hurd_check_ids ())
     HURD_PORT_USE (&_hurd_ports[INIT_PORT_PROC],
 		   __proc_setowner (port,
 				    (_hurd_id.gen.nuids
 				     ? _hurd_id.gen.uids[0] : 0),
 				    !_hurd_id.gen.nuids));
-  mutex_unlock (&_hurd_id.lock);
+  __mutex_unlock (&_hurd_id.lock);
 
   (void) &reauth_proc;		/* Silence compiler warning.  */
 }
diff --git a/hurd/setauth.c b/hurd/setauth.c
index deece2010a..025be580e1 100644
--- a/hurd/setauth.c
+++ b/hurd/setauth.c
@@ -18,14 +18,13 @@
 #include <hurd.h>
 #include <hurd/port.h>
 #include <hurd/id.h>
+#include <hurdlock.h>
 #include "set-hooks.h"
 
 /* Things in the library which want to be run when the auth port changes.  */
 DEFINE_HOOK (_hurd_reauth_hook, (auth_t new_auth));
 
-#include <cthreads.h>
-static struct mutex reauth_lock = MUTEX_INITIALIZER;
-
+static unsigned int reauth_lock = LLL_INITIALIZER;
 
 /* Set the auth port to NEW, and reauthenticate
    everything used by the library.  */
diff --git a/mach/Makefile b/mach/Makefile
index e0d1ffb1fa..2683587b2d 100644
--- a/mach/Makefile
+++ b/mach/Makefile
@@ -23,7 +23,7 @@ headers = mach_init.h mach.h mach_error.h mach-shortcuts.h mach/mach_traps.h \
 	  $(interface-headers) mach/mach.h mach/mig_support.h mach/error.h \
 	  $(lock-headers) machine-sp.h bits/mach/param.h
 lock = spin-solid spin-lock mutex-init mutex-solid
-lock-headers = lock-intern.h machine-lock.h spin-lock.h
+lock-headers = lock-intern.h spin-lock.h
 routines = $(mach-syscalls) $(mach-shortcuts) \
 	   mach_init mig_strncpy msg \
 	   mig-alloc mig-dealloc mig-reply \
diff --git a/mach/lock-intern.h b/mach/lock-intern.h
index f8874c7561..ed8acb6aec 100644
--- a/mach/lock-intern.h
+++ b/mach/lock-intern.h
@@ -19,12 +19,19 @@
 #define	_LOCK_INTERN_H
 
 #include <sys/cdefs.h>
-#include <machine-lock.h>
+#if defined __USE_EXTERN_INLINES && defined _LIBC
+# include <lowlevellock.h>
+#endif
 
 #ifndef _EXTERN_INLINE
 #define _EXTERN_INLINE __extern_inline
 #endif
 
+/* The type of a spin lock variable.  */
+typedef unsigned int __spin_lock_t;
+
+/* Static initializer for spinlocks.  */
+#define __SPIN_LOCK_INITIALIZER   LLL_INITIALIZER
 
 /* Initialize LOCK.  */
 
@@ -50,31 +57,47 @@ extern void __spin_lock (__spin_lock_t *__lock);
 _EXTERN_INLINE void
 __spin_lock (__spin_lock_t *__lock)
 {
-  if (! __spin_try_lock (__lock))
-    __spin_lock_solid (__lock);
+  lll_lock (__lock, 0);
 }
 #endif
-
-/* Name space-clean internal interface to mutex locks.
 
-   Code internal to the C library uses these functions to lock and unlock
-   mutex locks.  These locks are of type `struct mutex', defined in
-   <cthreads.h>.  The functions here are name space-clean.  If the program
-   is linked with the cthreads library, `__mutex_lock_solid' and
-   `__mutex_unlock_solid' will invoke the corresponding cthreads functions
-   to implement real mutex locks.  If not, simple stub versions just use
-   spin locks.  */
+/* Unlock LOCK.  */
+extern void __spin_unlock (__spin_lock_t *__lock);
 
+#if defined __USE_EXTERN_INLINES && defined _LIBC
+_EXTERN_INLINE void
+__spin_unlock (__spin_lock_t *__lock)
+{
+  lll_unlock (__lock, 0);
+}
+#endif
 
-/* Initialize the newly allocated mutex lock LOCK for further use.  */
-extern void __mutex_init (void *__lock);
+/* Try to lock LOCK; return nonzero if we locked it, zero if another has.  */
+extern int __spin_try_lock (__spin_lock_t *__lock);
 
-/* Lock LOCK, blocking if we can't get it.  */
-extern void __mutex_lock_solid (void *__lock);
+#if defined __USE_EXTERN_INLINES && defined _LIBC
+_EXTERN_INLINE int
+__spin_try_lock (__spin_lock_t *__lock)
+{
+  return (lll_trylock (__lock) == 0);
+}
+#endif
+
+/* Return nonzero if LOCK is locked.  */
+extern int __spin_lock_locked (__spin_lock_t *__lock);
 
-/* Finish unlocking LOCK, after the spin lock LOCK->held has already been
-   unlocked.  This function will wake up any thread waiting on LOCK.  */
-extern void __mutex_unlock_solid (void *__lock);
+#if defined __USE_EXTERN_INLINES && defined _LIBC
+_EXTERN_INLINE int
+__spin_lock_locked (__spin_lock_t *__lock)
+{
+  return (*(volatile __spin_lock_t *)__lock != 0);
+}
+#endif
+
+/* Name space-clean internal interface to mutex locks.  */
+
+/* Initialize the newly allocated mutex lock LOCK for further use.  */
+extern void __mutex_init (void *__lock);
 
 /* Lock the mutex lock LOCK.  */
 
@@ -84,8 +107,7 @@ extern void __mutex_lock (void *__lock);
 _EXTERN_INLINE void
 __mutex_lock (void *__lock)
 {
-  if (! __spin_try_lock ((__spin_lock_t *) __lock))
-    __mutex_lock_solid (__lock);
+  __spin_lock ((__spin_lock_t *)__lock);
 }
 #endif
 
@@ -97,8 +119,7 @@ extern void __mutex_unlock (void *__lock);
 _EXTERN_INLINE void
 __mutex_unlock (void *__lock)
 {
-  __spin_unlock ((__spin_lock_t *) __lock);
-  __mutex_unlock_solid (__lock);
+  __spin_unlock ((__spin_lock_t *)__lock);
 }
 #endif
 
@@ -109,7 +130,7 @@ extern int __mutex_trylock (void *__lock);
 _EXTERN_INLINE int
 __mutex_trylock (void *__lock)
 {
-  return __spin_try_lock ((__spin_lock_t *) __lock);
+  return (__spin_try_lock ((__spin_lock_t *)__lock));
 }
 #endif
 
diff --git a/mach/lowlevellock.h b/mach/lowlevellock.h
new file mode 100644
index 0000000000..20c66ca979
--- /dev/null
+++ b/mach/lowlevellock.h
@@ -0,0 +1,81 @@
+/* Low-level lock implementation.  Mach gsync-based version.
+   Copyright (C) 1994-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _MACH_LOWLEVELLOCK_H
+#define _MACH_LOWLEVELLOCK_H   1
+
+#include <mach/gnumach.h>
+#include <atomic.h>
+
+/* Gsync flags.  */
+#ifndef GSYNC_SHARED
+  #define GSYNC_SHARED      0x01
+  #define GSYNC_QUAD        0x02
+  #define GSYNC_TIMED       0x04
+  #define GSYNC_BROADCAST   0x08
+  #define GSYNC_MUTATE      0x10
+#endif
+
+/* Static initializer for low-level locks.  */
+#define LLL_INITIALIZER   0
+
+/* Wait on address PTR, without blocking if its contents
+ * are different from VAL.  */
+#define lll_wait(ptr, val, flags)   \
+  __gsync_wait (__mach_task_self (),   \
+    (vm_offset_t)(ptr), (val), 0, 0, (flags))
+
+/* Wake one or more threads waiting on address PTR.  */
+#define lll_wake(ptr, flags)   \
+  __gsync_wake (__mach_task_self (), (vm_offset_t)(ptr), 0, (flags))
+
+/* Acquire the lock at PTR.  */
+#define lll_lock(ptr, flags)   \
+  ({   \
+     int *__iptr = (int *)(ptr);   \
+     int __flags = (flags);   \
+     if (*__iptr != 0 ||   \
+         atomic_compare_and_exchange_bool_acq (__iptr, 1, 0) != 0)   \
+       while (1)   \
+         {   \
+           if (atomic_exchange_acq (__iptr, 2) == 0)   \
+             break;   \
+           lll_wait (__iptr, 2, __flags);   \
+         }   \
+     (void)0;   \
+   })
+
+/* Try to acquire the lock at PTR, without blocking.
+   Evaluates to zero on success.  */
+#define lll_trylock(ptr)   \
+  ({   \
+     int *__iptr = (int *)(ptr);   \
+     *__iptr == 0 &&   \
+       atomic_compare_and_exchange_bool_acq (__iptr, 1, 0) == 0 ? 0 : -1;   \
+   })
+
+/* Release the lock at PTR.  */
+#define lll_unlock(ptr, flags)   \
+  ({   \
+     int *__iptr = (int *)(ptr);   \
+     if (atomic_exchange_rel (__iptr, 0) == 2)   \
+       lll_wake (__iptr, (flags));   \
+     (void)0;   \
+   })
+
+#endif
diff --git a/mach/mutex-init.c b/mach/mutex-init.c
index cab0a86fec..776fec5506 100644
--- a/mach/mutex-init.c
+++ b/mach/mutex-init.c
@@ -17,13 +17,10 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <lock-intern.h>
-#include <cthreads.h>
+#include <lowlevellock.h>
 
 void
 __mutex_init (void *lock)
 {
-  /* This happens to be name space-safe because it is a macro.
-     It invokes only spin_lock_init, which is a macro for __spin_lock_init;
-     and cthread_queue_init, which is a macro for some simple code.  */
-  mutex_init ((struct mutex *) lock);
+  *(int *)lock = LLL_INITIALIZER;
 }
diff --git a/manual/errno.texi b/manual/errno.texi
index 73272fd884..8917cccb1e 100644
--- a/manual/errno.texi
+++ b/manual/errno.texi
@@ -882,6 +882,16 @@ the normal result is for the operations affected to complete with this
 error; @pxref{Cancel AIO Operations}.
 @end deftypevr
 
+@deftypevr Macro int EOWNERDEAD
+@standards{GNU, errno.h}
+@errno{EOWNERDEAD, 120, Owner died}
+@end deftypevr
+
+@deftypevr Macro int ENOTRECOVERABLE
+@standards{GNU, errno.h}
+@errno{ENOTRECOVERABLE, 121, State not recoverable}
+@end deftypevr
+
 
 @emph{The following error codes are defined by the Linux/i386 kernel.
 They are not yet documented.}
diff --git a/sysdeps/mach/Makefile b/sysdeps/mach/Makefile
index 2b48b13f61..475894b046 100644
--- a/sysdeps/mach/Makefile
+++ b/sysdeps/mach/Makefile
@@ -50,4 +50,30 @@ mach-before-compile:
 before-compile += $(mach-before-compile)
 endif
 
+ifeq (crypt,$(subdir))
+  LDLIBS-crypt.so += $(objdir)/mach/libmachuser.so
+else ifeq (dlfcn,$(subdir))
+  LDLIBS-dl.so += $(objdir)/mach/libmachuser.so
+else ifeq (nis,$(subdir))
+  LDLIBS-nsl.so += $(objdir)/mach/libmachuser.so
+  LDLIBS-nss_nis.so += $(objdir)/mach/libmachuser.so
+  LDLIBS-nss_nisplus.so += $(objdir)/mach/libmachuser.so
+  LDLIBS-nss_compat.so += $(objdir)/mach/libmachuser.so
+else ifeq (nss,$(subdir))
+  LDLIBS-nss.so += $(objdir)/mach/libmachuser.so
+  LDLIBS-nss_files.so += $(objdir)/mach/libmachuser.so
+  LDLIBS-nss_db.so += $(objdir)/mach/libmachuser.so
+  LDLIBS-nss_compat.so += $(objdir)/mach/libmachuser.so
+else ifeq (hesiod,$(subdir))
+  LDLIBS-nss_hesiod.so += $(objdir)/mach/libmachuser.so
+else ifeq (posix,$(subdir))
+  LDLIBS-tst-rfc3484 += $(objdir)/mach/libmachuser.so
+  LDLIBS-tst-rfc3484-2 += $(objdir)/mach/libmachuser.so
+  LDLIBS-tst-rfc3484-3 += $(objdir)/mach/libmachuser.so
+else ifeq (nscd,$(subdir))
+  LDLIBS-nscd += $(objdir)/mach/libmachuser.so
+endif
+
+LDLIBS-pthread.so += $(objdir)/mach/libmachuser.so
+
 endif	# in-Makerules
diff --git a/sysdeps/mach/hurd/bits/errno.h b/sysdeps/mach/hurd/bits/errno.h
index f16cd51a63..999730721f 100644
--- a/sysdeps/mach/hurd/bits/errno.h
+++ b/sysdeps/mach/hurd/bits/errno.h
@@ -127,6 +127,8 @@ enum __error_t_codes
   EPROTO                         = 0x40000074,	/* Protocol error */
   ETIME                          = 0x40000075,	/* Timer expired */
   ECANCELED                      = 0x40000077,	/* Operation canceled */
+  EOWNERDEAD                     = 0x40000078,	/* Robust mutex owner died */
+  ENOTRECOVERABLE                = 0x40000079,	/* Robust mutex irrecoverable */
 
 /* Errors from <mach/message.h>.  */
   EMACH_SEND_IN_PROGRESS         = 0x10000001,
@@ -322,6 +324,8 @@ enum __error_t_codes
 #define EPROTO                         0x40000074
 #define ETIME                          0x40000075
 #define ECANCELED                      0x40000077
+#define EOWNERDEAD                     0x40000078
+#define ENOTRECOVERABLE                0x40000079
 
 /* Errors from <mach/message.h>.  */
 #define EMACH_SEND_IN_PROGRESS         0x10000001
@@ -405,6 +409,6 @@ enum __error_t_codes
 #define ED_NO_MEMORY                   2508
 #define ED_READ_ONLY                   2509
 
-#define _HURD_ERRNOS 120
+#define _HURD_ERRNOS 122
 
 #endif /* bits/errno.h.  */
diff --git a/sysdeps/mach/hurd/cthreads.c b/sysdeps/mach/hurd/cthreads.c
index 585650522a..05c48e4e4c 100644
--- a/sysdeps/mach/hurd/cthreads.c
+++ b/sysdeps/mach/hurd/cthreads.c
@@ -52,13 +52,3 @@ __cthread_setspecific (cthread_key_t key, void *val)
   __set_errno (ENOSYS);
   return -1;
 }
-
-/* Call cthread_getspecific which gets a pointer to the return value instead
-   of just returning it.  */
-void *
-__libc_getspecific (cthread_key_t key)
-{
-  void *val;
-  __cthread_getspecific (key, &val);
-  return val;
-}
diff --git a/sysdeps/mach/hurd/libc-lock.h b/sysdeps/mach/hurd/libc-lock.h
deleted file mode 100644
index f5a1f66a23..0000000000
--- a/sysdeps/mach/hurd/libc-lock.h
+++ /dev/null
@@ -1,216 +0,0 @@
-/* libc-internal interface for mutex locks.  Hurd version using Mach cthreads.
-   Copyright (C) 1996-2018 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <http://www.gnu.org/licenses/>.  */
-
-#ifndef _LIBC_LOCK_H
-#define _LIBC_LOCK_H 1
-
-#if (_LIBC - 0) || (_CTHREADS_ - 0)
-#include <cthreads.h>
-
-/* The locking here is very inexpensive, even for inlining.  */
-#define _IO_lock_inexpensive  1
-
-typedef struct mutex __libc_lock_t;
-typedef struct
-{
-  struct mutex mutex;
-  void *owner;
-  int count;
-} __libc_lock_recursive_t;
-typedef __libc_lock_recursive_t __rtld_lock_recursive_t;
-
-extern char __libc_lock_self0[0];
-#define __libc_lock_owner_self() (__LIBC_NO_TLS () ? &__libc_lock_self0 : THREAD_SELF)
-
-#else
-typedef struct __libc_lock_opaque__ __libc_lock_t;
-typedef struct __libc_lock_recursive_opaque__ __libc_lock_recursive_t;
-#endif
-
-/* Define a lock variable NAME with storage class CLASS.  The lock must be
-   initialized with __libc_lock_init before it can be used (or define it
-   with __libc_lock_define_initialized, below).  Use `extern' for CLASS to
-   declare a lock defined in another module.  In public structure
-   definitions you must use a pointer to the lock structure (i.e., NAME
-   begins with a `*'), because its storage size will not be known outside
-   of libc.  */
-#define __libc_lock_define(CLASS,NAME) \
-  CLASS __libc_lock_t NAME;
-
-/* Define an initialized lock variable NAME with storage class CLASS.  */
-#define _LIBC_LOCK_INITIALIZER MUTEX_INITIALIZER
-#define __libc_lock_define_initialized(CLASS,NAME) \
-  CLASS __libc_lock_t NAME = _LIBC_LOCK_INITIALIZER;
-
-/* Initialize the named lock variable, leaving it in a consistent, unlocked
-   state.  */
-#define __libc_lock_init(NAME) __mutex_init (&(NAME))
-
-/* Finalize the named lock variable, which must be locked.  It cannot be
-   used again until __libc_lock_init is called again on it.  This must be
-   called on a lock variable before the containing storage is reused.  */
-#define __libc_lock_fini(NAME) __mutex_unlock (&(NAME))
-#define __libc_lock_fini_recursive(NAME) __mutex_unlock (&(NAME).mutex)
-#define __rtld_lock_fini_recursive(NAME) __mutex_unlock (&(NAME).mutex)
-
-
-/* Lock the named lock variable.  */
-#define __libc_lock_lock(NAME) __mutex_lock (&(NAME))
-
-/* Lock the named lock variable.  */
-#define __libc_lock_trylock(NAME) (!__mutex_trylock (&(NAME)))
-
-/* Unlock the named lock variable.  */
-#define __libc_lock_unlock(NAME) __mutex_unlock (&(NAME))
-
-
-#define __libc_lock_define_recursive(CLASS,NAME) \
-  CLASS __libc_lock_recursive_t NAME;
-#define _LIBC_LOCK_RECURSIVE_INITIALIZER { MUTEX_INITIALIZER, 0, 0 }
-#define __libc_lock_define_initialized_recursive(CLASS,NAME) \
-  CLASS __libc_lock_recursive_t NAME = _LIBC_LOCK_RECURSIVE_INITIALIZER;
-
-#define __rtld_lock_define_recursive(CLASS,NAME) \
-  __libc_lock_define_recursive (CLASS, NAME)
-#define _RTLD_LOCK_RECURSIVE_INITIALIZER \
-  _LIBC_LOCK_RECURSIVE_INITIALIZER
-#define __rtld_lock_define_initialized_recursive(CLASS,NAME) \
-  __libc_lock_define_initialized_recursive (CLASS, NAME)
-
-#define __libc_lock_init_recursive(NAME) \
-  ({ __libc_lock_recursive_t *const __lock = &(NAME); \
-     __lock->owner = 0; mutex_init (&__lock->mutex); })
-
-#define __libc_lock_trylock_recursive(NAME)				      \
-  ({ __libc_lock_recursive_t *const __lock = &(NAME);			      \
-     void *__self = __libc_lock_owner_self ();				      \
-     __mutex_trylock (&__lock->mutex)					      \
-     ? (__lock->owner = __self, __lock->count = 1, 0)			      \
-     : __lock->owner == __self ? (++__lock->count, 0) : 1; })
-
-#define __libc_lock_lock_recursive(NAME)				      \
-  ({ __libc_lock_recursive_t *const __lock = &(NAME);			      \
-     void *__self = __libc_lock_owner_self ();				      \
-     if (__mutex_trylock (&__lock->mutex)				      \
-	 || (__lock->owner != __self					      \
-	     && (__mutex_lock (&__lock->mutex), 1)))			      \
-       __lock->owner = __self, __lock->count = 1;			      \
-     else								      \
-       ++__lock->count;							      \
-  })
-#define __libc_lock_unlock_recursive(NAME)				      \
-  ({ __libc_lock_recursive_t *const __lock = &(NAME);			      \
-     if (--__lock->count == 0)						      \
-       {								      \
-	 __lock->owner = 0;						      \
-	 __mutex_unlock (&__lock->mutex);				      \
-       }								      \
-  })
-
-
-#define __rtld_lock_initialize(NAME) \
-  (void) ((NAME) = (__rtld_lock_recursive_t) _RTLD_LOCK_RECURSIVE_INITIALIZER)
-#define __rtld_lock_trylock_recursive(NAME) \
-  __libc_lock_trylock_recursive (NAME)
-#define __rtld_lock_lock_recursive(NAME) \
-  __libc_lock_lock_recursive(NAME)
-#define __rtld_lock_unlock_recursive(NAME) \
-  __libc_lock_unlock_recursive (NAME)
-
-
-/* XXX for now */
-#define __libc_rwlock_define		__libc_lock_define
-#define __libc_rwlock_define_initialized __libc_lock_define_initialized
-#define __libc_rwlock_init		__libc_lock_init
-#define __libc_rwlock_fini		__libc_lock_fini
-#define __libc_rwlock_rdlock		__libc_lock_lock
-#define __libc_rwlock_wrlock		__libc_lock_lock
-#define __libc_rwlock_tryrdlock		__libc_lock_trylock
-#define __libc_rwlock_trywrlock		__libc_lock_trylock
-#define __libc_rwlock_unlock		__libc_lock_unlock
-
-
-/* Start a critical region with a cleanup function */
-#define __libc_cleanup_region_start(DOIT, FCT, ARG)			    \
-{									    \
-  typeof (***(FCT)) *__save_FCT = (DOIT) ? (FCT) : 0;			    \
-  typeof (ARG) __save_ARG = ARG;					    \
-  /* close brace is in __libc_cleanup_region_end below. */
-
-/* End a critical region started with __libc_cleanup_region_start. */
-#define __libc_cleanup_region_end(DOIT)					    \
-  if ((DOIT) && __save_FCT != 0)					    \
-    (*__save_FCT)(__save_ARG);						    \
-}
-
-/* Sometimes we have to exit the block in the middle.  */
-#define __libc_cleanup_end(DOIT)					    \
-  if ((DOIT) && __save_FCT != 0)					    \
-    (*__save_FCT)(__save_ARG);						    \
-
-#define __libc_cleanup_push(fct, arg) __libc_cleanup_region_start (1, fct, arg)
-#define __libc_cleanup_pop(execute) __libc_cleanup_region_end (execute)
-
-#if (_CTHREADS_ - 0)
-
-/* Use mutexes as once control variables. */
-
-struct __libc_once
-  {
-    __libc_lock_t lock;
-    int done;
-  };
-
-#define __libc_once_define(CLASS,NAME) \
-  CLASS struct __libc_once NAME = { MUTEX_INITIALIZER, 0 }
-
-/* Call handler iff the first call.  */
-#define __libc_once(ONCE_CONTROL, INIT_FUNCTION) \
-  do {									      \
-    __libc_lock_lock (ONCE_CONTROL.lock);				      \
-    if (!ONCE_CONTROL.done)						      \
-      (INIT_FUNCTION) ();						      \
-    ONCE_CONTROL.done = 1;						      \
-    __libc_lock_unlock (ONCE_CONTROL.lock);				      \
-  } while (0)
-
-/* Get once control variable.  */
-#define __libc_once_get(ONCE_CONTROL)	((ONCE_CONTROL).done != 0)
-
-#ifdef _LIBC
-/* We need portable names for some functions.  E.g., when they are
-   used as argument to __libc_cleanup_region_start.  */
-#define __libc_mutex_unlock __mutex_unlock
-#endif
-
-/* Type for key of thread specific data.  */
-typedef cthread_key_t __libc_key_t;
-
-#define __libc_key_create(KEY,DEST) __cthread_keycreate (KEY)
-#define __libc_setspecific(KEY,VAL) __cthread_setspecific (KEY, VAL)
-void *__libc_getspecific (__libc_key_t key);
-
-#endif /* _CTHREADS_ */
-
-/* Hide the definitions which are only supposed to be used inside libc in
-   a separate file.  This file is not present in the installation!  */
-#ifdef _LIBC
-# include <libc-lockP.h>
-#endif
-
-#endif	/* libc-lock.h */
diff --git a/sysdeps/mach/hurd/setpgid.c b/sysdeps/mach/hurd/setpgid.c
index 32186a25de..98b1341cfa 100644
--- a/sysdeps/mach/hurd/setpgid.c
+++ b/sysdeps/mach/hurd/setpgid.c
@@ -19,6 +19,7 @@
 #include <unistd.h>
 #include <hurd.h>
 #include <hurd/port.h>
+#include <lowlevellock.h>
 
 /* Set the process group ID of the process matching PID to PGID.
    If PID is zero, the current process's process group ID is set.
@@ -38,14 +39,7 @@ __setpgid (pid_t pid, pid_t pgid)
     /* Synchronize with the signal thread to make sure we have
        received and processed proc_newids before returning to the user.  */
     while (_hurd_pids_changed_stamp == stamp)
-      {
-#ifdef noteven
-	/* XXX we have no need for a mutex, but cthreads demands one.  */
-	__condition_wait (&_hurd_pids_changed_sync, NULL);
-#else
-	__swtch_pri(0);
-#endif
-      }
+      lll_wait (&_hurd_pids_changed_stamp, stamp, 0);
 
   return 0;
 
diff --git a/sysdeps/mach/hurd/setsid.c b/sysdeps/mach/hurd/setsid.c
index 0f6b24b1d2..7b989361d1 100644
--- a/sysdeps/mach/hurd/setsid.c
+++ b/sysdeps/mach/hurd/setsid.c
@@ -21,6 +21,7 @@
 #include <hurd/port.h>
 #include <hurd/fd.h>
 #include <hurd/ioctl.h>
+#include <lowlevellock.h>
 
 /* Create a new session with the calling process as its leader.
    The process group IDs of the session and the calling process
@@ -55,14 +56,7 @@ __setsid (void)
 	 returned by `getpgrp ()' in other threads) has been updated before
 	 we return.  */
       while (_hurd_pids_changed_stamp == stamp)
-	{
-#ifdef noteven
-	  /* XXX we have no need for a mutex, but cthreads demands one.  */
-	  __condition_wait (&_hurd_pids_changed_sync, NULL);
-#else
-	  __swtch_pri (0);
-#endif
-	}
+        lll_wait (&_hurd_pids_changed_stamp, stamp, 0);
     }
 
   HURD_CRITICAL_END;
diff --git a/sysdeps/mach/libc-lock.h b/sysdeps/mach/libc-lock.h
index 1bb0235cf2..2c64019b33 100644
--- a/sysdeps/mach/libc-lock.h
+++ b/sysdeps/mach/libc-lock.h
@@ -20,15 +20,32 @@
 #define _LIBC_LOCK_H 1
 
 #ifdef _LIBC
-#include <cthreads.h>
-#define __libc_lock_t struct mutex
+
+#include <tls.h>
+#include <lowlevellock.h>
+
+/* The locking here is very inexpensive, even for inlining.  */
+#define _IO_lock_inexpensive   1
+
+typedef unsigned int __libc_lock_t;
+typedef struct
+{
+  __libc_lock_t lock;
+  int cnt;
+  void *owner;
+} __libc_lock_recursive_t;
+
+typedef __libc_lock_recursive_t __rtld_lock_recursive_t;
+
+extern char __libc_lock_self0[0];
+#define __libc_lock_owner_self()   \
+  (__LIBC_NO_TLS () ? (void *)&__libc_lock_self0 : THREAD_SELF)
+
 #else
 typedef struct __libc_lock_opaque__ __libc_lock_t;
+typedef struct __libc_lock_recursive_opaque__ __libc_lock_recursive_t;
 #endif
 
-/* Type for key of thread specific data.  */
-typedef cthread_key_t __libc_key_t;
-
 /* Define a lock variable NAME with storage class CLASS.  The lock must be
    initialized with __libc_lock_init before it can be used (or define it
    with __libc_lock_define_initialized, below).  Use `extern' for CLASS to
@@ -40,27 +57,97 @@ typedef cthread_key_t __libc_key_t;
   CLASS __libc_lock_t NAME;
 
 /* Define an initialized lock variable NAME with storage class CLASS.  */
+#define _LIBC_LOCK_INITIALIZER LLL_INITIALIZER
 #define __libc_lock_define_initialized(CLASS,NAME) \
-  CLASS __libc_lock_t NAME = MUTEX_INITIALIZER;
+  CLASS __libc_lock_t NAME = LLL_INITIALIZER;
 
 /* Initialize the named lock variable, leaving it in a consistent, unlocked
    state.  */
-#define __libc_lock_init(NAME) __mutex_init (&(NAME))
+#define __libc_lock_init(NAME) (NAME) = LLL_INITIALIZER
 
 /* Finalize the named lock variable, which must be locked.  It cannot be
    used again until __libc_lock_init is called again on it.  This must be
    called on a lock variable before the containing storage is reused.  */
-#define __libc_lock_fini(NAME) __mutex_unlock (&(NAME))
+#define __libc_lock_fini             __libc_lock_unlock
+#define __libc_lock_fini_recursive   __libc_lock_unlock_recursive
+#define __rtld_lock_fini_recursive   __rtld_lock_unlock_recursive
 
 /* Lock the named lock variable.  */
-#define __libc_lock_lock(NAME) __mutex_lock (&(NAME))
+#define __libc_lock_lock(NAME)   \
+  ({ lll_lock (&(NAME), 0); 0; })
 
 /* Lock the named lock variable.  */
-#define __libc_lock_trylock(NAME) (!__mutex_trylock (&(NAME)))
+#define __libc_lock_trylock(NAME) lll_trylock (&(NAME))
 
 /* Unlock the named lock variable.  */
-#define __libc_lock_unlock(NAME) __mutex_unlock (&(NAME))
-
+#define __libc_lock_unlock(NAME)   \
+  ({ lll_unlock (&(NAME), 0); 0; })
+
+#define __libc_lock_define_recursive(CLASS,NAME) \
+  CLASS __libc_lock_recursive_t NAME;
+
+#define _LIBC_LOCK_RECURSIVE_INITIALIZER { LLL_INITIALIZER, 0, 0 }
+
+#define __libc_lock_define_initialized_recursive(CLASS,NAME) \
+  CLASS __libc_lock_recursive_t NAME = _LIBC_LOCK_RECURSIVE_INITIALIZER;
+
+#define __rtld_lock_define_recursive(CLASS,NAME) \
+  __libc_lock_define_recursive (CLASS, NAME)
+#define _RTLD_LOCK_RECURSIVE_INITIALIZER \
+  _LIBC_LOCK_RECURSIVE_INITIALIZER
+#define __rtld_lock_define_initialized_recursive(CLASS,NAME) \
+  __libc_lock_define_initialized_recursive (CLASS, NAME)
+
+#define __libc_lock_init_recursive(NAME)   \
+  ({   \
+     (NAME) = (__libc_lock_recursive_t)_LIBC_LOCK_RECURSIVE_INITIALIZER;   \
+     0;   \
+  })
+
+#define __libc_lock_trylock_recursive(NAME)   \
+  ({   \
+     __libc_lock_recursive_t *const __lock = &(NAME);   \
+     void *__self = __libc_lock_owner_self ();   \
+     int __r = 0;   \
+     if (__self == __lock->owner)   \
+       ++__lock->cnt;   \
+     else if ((__r = lll_trylock (&__lock->lock)) == 0)   \
+       __lock->owner = __self, __lock->cnt = 1;   \
+     __r;   \
+   })
+
+#define __libc_lock_lock_recursive(NAME)   \
+  ({   \
+     __libc_lock_recursive_t *const __lock = &(NAME);   \
+     void *__self = __libc_lock_owner_self ();   \
+     if (__self != __lock->owner)   \
+       {   \
+         lll_lock (&__lock->lock, 0);   \
+         __lock->owner = __self;   \
+       }   \
+     ++__lock->cnt;   \
+     (void)0;   \
+   })
+
+#define __libc_lock_unlock_recursive(NAME)   \
+  ({   \
+     __libc_lock_recursive_t *const __lock = &(NAME);   \
+     if (--__lock->cnt == 0)   \
+       {   \
+         __lock->owner = 0;   \
+         lll_unlock (&__lock->lock, 0);   \
+       }   \
+   })
+
+
+#define __rtld_lock_initialize(NAME) \
+  (void) ((NAME) = (__rtld_lock_recursive_t) _RTLD_LOCK_RECURSIVE_INITIALIZER)
+#define __rtld_lock_trylock_recursive(NAME) \
+  __libc_lock_trylock_recursive (NAME)
+#define __rtld_lock_lock_recursive(NAME) \
+  __libc_lock_lock_recursive(NAME)
+#define __rtld_lock_unlock_recursive(NAME) \
+  __libc_lock_unlock_recursive (NAME)
 
 /* XXX for now */
 #define __libc_rwlock_define		__libc_lock_define
@@ -95,7 +182,7 @@ __libc_cleanup_fct (struct __libc_cleanup_frame *framep)
         __attribute__ ((__cleanup__ (__libc_cleanup_fct))) =   \
         { .__fct = (FCT), .__argp = (ARG), .__doit = (DOIT) };
 
-/* This one closes the brace above. */
+/* This one closes the brace above.  */
 #define __libc_cleanup_region_end(DOIT)   \
       __cleanup.__doit = (DOIT);   \
     }   \
@@ -106,7 +193,7 @@ __libc_cleanup_fct (struct __libc_cleanup_frame *framep)
 #define __libc_cleanup_push(fct, arg) __libc_cleanup_region_start (1, fct, arg)
 #define __libc_cleanup_pop(execute) __libc_cleanup_region_end (execute)
 
-/* Use mutexes as once control variables. */
+/* Use mutexes as once control variables.  */
 
 struct __libc_once
   {
@@ -115,8 +202,7 @@ struct __libc_once
   };
 
 #define __libc_once_define(CLASS,NAME) \
-  CLASS struct __libc_once NAME = { MUTEX_INITIALIZER, 0 }
-
+  CLASS struct __libc_once NAME = { _LIBC_LOCK_INITIALIZER, 0 }
 
 /* Call handler iff the first call.  */
 #define __libc_once(ONCE_CONTROL, INIT_FUNCTION) \
@@ -134,25 +220,11 @@ struct __libc_once
 #ifdef _LIBC
 /* We need portable names for some functions.  E.g., when they are
    used as argument to __libc_cleanup_region_start.  */
-#define __libc_mutex_unlock __mutex_unlock
-#endif
+#define __libc_mutex_unlock __libc_lock_unlock
 
-#define __libc_key_create(KEY,DEST) __cthread_keycreate (KEY)
-#define __libc_setspecific(KEY,VAL) __cthread_setspecific (KEY, VAL)
-void *__libc_getspecific (__libc_key_t key);
-
-/* XXX until cthreads supports recursive locks */
-#define __libc_lock_define_initialized_recursive __libc_lock_define_initialized
-#define __libc_lock_init_recursive __libc_lock_init
-#define __libc_lock_fini_recursive __libc_lock_fini
-#define __libc_lock_trylock_recursive __libc_lock_trylock
-#define __libc_lock_unlock_recursive __libc_lock_unlock
-#define __libc_lock_lock_recursive __libc_lock_lock
-
-#define __rtld_lock_define_initialized_recursive __libc_lock_define_initialized
-#define __rtld_lock_fini_recursive __libc_lock_fini
-#define __rtld_lock_trylock_recursive __libc_lock_trylock
-#define __rtld_lock_unlock_recursive __libc_lock_unlock
-#define __rtld_lock_lock_recursive __libc_lock_lock
+/* Hide the definitions which are only supposed to be used inside libc in
+   a separate file.  This file is not present in the installation!  */
+# include <libc-lockP.h>
+#endif
 
 #endif	/* libc-lock.h */
