diff --git a/sys/compat/freebsd32/syscalls.master b/sys/compat/freebsd32/syscalls.master
index 42e98f2934ea..c6e95503d94a 100644
--- a/sys/compat/freebsd32/syscalls.master
+++ b/sys/compat/freebsd32/syscalls.master
@@ -604,3 +604,5 @@
 439	UNIMPL	extattr_list_link
 440	UNIMPL	kse_switchin
 441	UNIMPL	ksem_timedwait
+442     MNOPROTO { int thr_suspend(const struct timespec *timeout); }
+443     MNOPROTO { int thr_wake(thr_id_t id); }
diff --git a/sys/kern/kern_thr.c b/sys/kern/kern_thr.c
index eef25acbdf88..24aaaac02751 100644
--- a/sys/kern/kern_thr.c
+++ b/sys/kern/kern_thr.c
@@ -254,3 +254,64 @@ thr_kill(struct thread *td, struct thr_kill_args *uap)
 	PROC_UNLOCK(p);
 	return (error);
 }
+
+int
+thr_suspend(struct thread *td, struct thr_suspend_args *uap)
+	/* const struct timespec *timeout */
+{
+	struct timespec ts;
+	struct timeval	tv;
+	int error;
+	int hz;
+
+	hz = 0;
+	error = 0;
+	if (uap->timeout != NULL) {
+		error = copyin((const void *)uap->timeout, (void *)&ts,
+		    sizeof(struct timespec));
+		if (error != 0)
+			return (error);
+		if (ts.tv_nsec < 0 || ts.tv_nsec > 1000000000)
+			return (EINVAL);
+		if (ts.tv_sec == 0 && ts.tv_nsec == 0)
+			return (ETIMEDOUT);
+		TIMESPEC_TO_TIMEVAL(&tv, &ts);
+		hz = tvtohz(&tv);
+	}
+	PROC_LOCK(td->td_proc);
+	mtx_lock_spin(&sched_lock);
+	if ((td->td_flags & TDF_THRWAKEUP) == 0) {
+		mtx_unlock_spin(&sched_lock);
+		error = msleep((void *)td, &td->td_proc->p_mtx,
+		    td->td_priority | PCATCH, "lthr", hz);
+		mtx_lock_spin(&sched_lock);
+	}
+	td->td_flags &= ~TDF_THRWAKEUP;
+	mtx_unlock_spin(&sched_lock);
+	PROC_UNLOCK(td->td_proc);
+	return (error == EWOULDBLOCK ? ETIMEDOUT : error);
+}
+
+int
+thr_wake(struct thread *td, struct thr_wake_args *uap)
+	/* thr_id_t id */
+{
+	struct thread *tdsleeper, *ttd;
+
+	tdsleeper = ((struct thread *)uap->id);
+	PROC_LOCK(tdsleeper->td_proc);
+	FOREACH_THREAD_IN_PROC(tdsleeper->td_proc, ttd) {
+		if (ttd == tdsleeper)
+			break;
+	}
+	if (ttd == NULL) {
+		PROC_UNLOCK(tdsleeper->td_proc);
+		return (ESRCH);
+	}
+	mtx_lock_spin(&sched_lock);
+	tdsleeper->td_flags |= TDF_THRWAKEUP;
+	mtx_unlock_spin(&sched_lock);
+	wakeup_one((void *)tdsleeper);
+	PROC_UNLOCK(tdsleeper->td_proc);
+	return (0);
+}
diff --git a/sys/kern/syscalls.master b/sys/kern/syscalls.master
index ceddb974ef15..a5380b6c0af7 100644
--- a/sys/kern/syscalls.master
+++ b/sys/kern/syscalls.master
@@ -629,5 +629,7 @@
 440	MSTD	{ int kse_switchin(const struct __mcontext *mcp, \
 		    long val, long *loc); }
 441	MNOSTD	{ int ksem_timedwait(semid_t id, struct timespec *abstime); }
+442	MSTD	{ int thr_suspend(const struct timespec *timeout); }
+443	MSTD	{ int thr_wake(thr_id_t id); }
 ; Please copy any additions and changes to the following compatability tables:
 ; sys/compat/freebsd32/syscalls.master
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index 0534b87b9230..e067d3cfa601 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -356,6 +356,7 @@ struct thread {
 #define	TDF_NEEDSIGCHK	0x020000 /* Thread may need signal delivery. */
 #define	TDF_SA		0x040000 /* A scheduler activation based thread. */
 #define TDF_UMTXWAKEUP	0x080000 /* Libthr thread must not sleep on a umtx. */
+#define TDF_THRWAKEUP	0x100000 /* Libthr thread must not suspend itself. */
 #define	TDF_DEADLKTREAT	0x800000 /* Lock aquisition - deadlock treatment. */
 
 /* "private" flags kept in td_pflags */
diff --git a/sys/sys/thr.h b/sys/sys/thr.h
index 9869ce3dfeb2..cd0e732f4ff0 100644
--- a/sys/sys/thr.h
+++ b/sys/sys/thr.h
@@ -46,6 +46,8 @@ int thr_create(ucontext_t *ctx, thr_id_t *id, int flags);
 int thr_self(thr_id_t *id);
 void thr_exit(void);
 int thr_kill(thr_id_t id, int sig);
+int thr_suspend(const struct timespec *timeout);
+int thr_wake(thr_id_t id);
 
 #endif /* !_KERNEL */