Index: sys/kern/kern_thread.c
===================================================================
--- sys/kern/kern_thread.c
+++ sys/kern/kern_thread.c
@@ -44,6 +44,7 @@
 #include <sys/smp.h>
 #include <sys/sched.h>
 #include <sys/sleepqueue.h>
+#include <sys/sysent.h>
 #include <sys/selinfo.h>
 #include <sys/turnstile.h>
 #include <sys/ktr.h>
@@ -807,6 +808,12 @@
 		 */
 		if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) {
 			PROC_UNLOCK(p);
+			/*
+			 * Let thread to do cleanup work before die.
+			 */
+			if (__predict_false(p->p_sysent->sv_thread_detach != NULL))
+				(p->p_sysent->sv_thread_detach)(td);
+
 			tidhash_remove(td);
 			PROC_LOCK(p);
 			tdsigcleanup(td);
Index: sys/sys/sysent.h
===================================================================
--- sys/sys/sysent.h
+++ sys/sys/sysent.h
@@ -136,6 +136,7 @@
 	uint32_t	sv_timekeep_gen;
 	void		*sv_shared_page_obj;
 	void		(*sv_schedtail)(struct thread *);
+	void		(*sv_thread_detach)(struct thread *);
 };
 
 #define	SV_ILP32	0x000100