diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -1064,6 +1064,8 @@
 
 	sigfastblock_clear(td);
 	umtx_exec(p);
+	if (p->p_sysent->sv_onexec_old != NULL)
+		p->p_sysent->sv_onexec_old(td);
 	itimers_exec(p);
 	if (sv->sv_onexec != NULL)
 		sv->sv_onexec(p, imgp);
diff --git a/sys/sys/sysent.h b/sys/sys/sysent.h
--- a/sys/sys/sysent.h
+++ b/sys/sys/sysent.h
@@ -150,6 +150,7 @@
 	u_long		*sv_hwcap2;	/* Value passed in AT_HWCAP2. */
 	const char	*(*sv_machine_arch)(struct proc *);
 	vm_offset_t	sv_fxrng_gen_base;
+	void		(*sv_onexec_old)(struct thread *td);
 	void		(*sv_onexec)(struct proc *, struct image_params *);
 	void		(*sv_onexit)(struct proc *);
 	void		(*sv_ontdexit)(struct thread *td);