diff --git a/sys/amd64/amd64/elf_machdep.c b/sys/amd64/amd64/elf_machdep.c
index a3fb1184bb0..445efa883fd 100644
--- a/sys/amd64/amd64/elf_machdep.c
+++ b/sys/amd64/amd64/elf_machdep.c
@@ -82,6 +82,8 @@ struct sysentvec elf64_freebsd_sysvec_la48 = {
 	.sv_thread_detach = NULL,
 	.sv_trap	= NULL,
 	.sv_stackgap	= elf64_stackgap,
+	.sv_onexec_old	= exec_onexec_old,
+	.sv_onexit	= exit_onexit,
 };
 
 struct sysentvec elf64_freebsd_sysvec_la57 = {
@@ -117,6 +119,8 @@ struct sysentvec elf64_freebsd_sysvec_la57 = {
 	.sv_thread_detach = NULL,
 	.sv_trap	= NULL,
 	.sv_stackgap	= elf64_stackgap,
+	.sv_onexec_old	= exec_onexec_old,
+	.sv_onexit	= exit_onexit,
 };
 
 static void
diff --git a/sys/arm/arm/elf_machdep.c b/sys/arm/arm/elf_machdep.c
index d32dbb5baf9..6eaea9b92f2 100644
--- a/sys/arm/arm/elf_machdep.c
+++ b/sys/arm/arm/elf_machdep.c
@@ -97,6 +97,8 @@ struct sysentvec elf32_freebsd_sysvec = {
 	.sv_trap	= NULL,
 	.sv_hwcap	= &elf_hwcap,
 	.sv_hwcap2	= &elf_hwcap2,
+	.sv_onexec_old	= exec_onexec_old,
+	.sv_onexit	= exit_onexit,
 };
 INIT_SYSENTVEC(elf32_sysvec, &elf32_freebsd_sysvec);
 
diff --git a/sys/arm64/arm64/elf32_machdep.c b/sys/arm64/arm64/elf32_machdep.c
index 6c98f7c839c..48d6dc189e3 100644
--- a/sys/arm64/arm64/elf32_machdep.c
+++ b/sys/arm64/arm64/elf32_machdep.c
@@ -109,6 +109,8 @@ static struct sysentvec elf32_freebsd_sysvec = {
 	.sv_schedtail	= NULL,
 	.sv_thread_detach = NULL,
 	.sv_trap	= NULL,
+	.sv_onexec_old	= exec_onexec_old,
+	.sv_onexit	= exit_onexit,
 };
 INIT_SYSENTVEC(elf32_sysvec, &elf32_freebsd_sysvec);
 
diff --git a/sys/arm64/arm64/elf_machdep.c b/sys/arm64/arm64/elf_machdep.c
index cd12d40c37d..102097b2dbb 100644
--- a/sys/arm64/arm64/elf_machdep.c
+++ b/sys/arm64/arm64/elf_machdep.c
@@ -92,6 +92,8 @@ static struct sysentvec elf64_freebsd_sysvec = {
 	.sv_trap	= NULL,
 	.sv_hwcap	= &elf_hwcap,
 	.sv_hwcap2	= &elf_hwcap2,
+	.sv_onexec_old	= exec_onexec_old,
+	.sv_onexit	= exit_onexit,
 };
 INIT_SYSENTVEC(elf64_sysvec, &elf64_freebsd_sysvec);
 
diff --git a/sys/compat/ia32/ia32_sysvec.c b/sys/compat/ia32/ia32_sysvec.c
index f5a2c1200fc..3973811ab62 100644
--- a/sys/compat/ia32/ia32_sysvec.c
+++ b/sys/compat/ia32/ia32_sysvec.c
@@ -128,6 +128,8 @@ struct sysentvec ia32_freebsd_sysvec = {
 	.sv_thread_detach = NULL,
 	.sv_trap	= NULL,
 	.sv_stackgap	= elf32_stackgap,
+	.sv_onexec_old	= exec_onexec_old,
+	.sv_onexit	= exit_onexit,
 };
 INIT_SYSENTVEC(elf_ia32_sysvec, &ia32_freebsd_sysvec);
 
diff --git a/sys/i386/i386/elf_machdep.c b/sys/i386/i386/elf_machdep.c
index 0d870748967..ef808e65fd9 100644
--- a/sys/i386/i386/elf_machdep.c
+++ b/sys/i386/i386/elf_machdep.c
@@ -83,6 +83,8 @@ struct sysentvec elf32_freebsd_sysvec = {
 	.sv_schedtail	= NULL,
 	.sv_thread_detach = NULL,
 	.sv_trap	= NULL,
+	.sv_onexec_old	= exec_onexec_old,
+	.sv_onexit	= exit_onexit,
 };
 INIT_SYSENTVEC(elf32_sysvec, &elf32_freebsd_sysvec);
 
diff --git a/sys/kern/imgact_aout.c b/sys/kern/imgact_aout.c
index 3255ef169f7..9e7455e14e1 100644
--- a/sys/kern/imgact_aout.c
+++ b/sys/kern/imgact_aout.c
@@ -101,6 +101,8 @@ struct sysentvec aout_sysvec = {
 	.sv_schedtail	= NULL,
 	.sv_thread_detach = NULL,
 	.sv_trap	= NULL,
+	.sv_onexec_old = exec_onexec_old,
+	.sv_onexit =  exit_onexit,
 };
 
 #elif defined(__amd64__)
@@ -137,6 +139,8 @@ struct sysentvec aout_sysvec = {
 	.sv_set_syscall_retval = ia32_set_syscall_retval,
 	.sv_fetch_syscall_args = ia32_fetch_syscall_args,
 	.sv_syscallnames = freebsd32_syscallnames,
+	.sv_onexec_old	= exec_onexec_old,
+	.sv_onexit	= exit_onexit,
 };
 #else
 #error "Port me"
diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index de1294ff695..491e5332c83 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -1033,6 +1033,13 @@ exec_unmap_first_page(struct image_params *imgp)
 	}
 }
 
+void
+exec_onexec_old(struct thread *td)
+{
+	sigfastblock_clear(td);
+	umtx_exec(td->td_proc);
+}
+
 /*
  * Destroy old address space, and allocate a new stack.
  *	The new stack is only sgrowsiz large because it is grown
@@ -1055,8 +1062,6 @@ exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv)
 	imgp->vmspace_destroyed = 1;
 	imgp->sysent = sv;
 
-	sigfastblock_clear(td);
-	umtx_exec(p);
 	if (p->p_sysent->sv_onexec_old != NULL)
 		p->p_sysent->sv_onexec_old(td);
 	itimers_exec(p);
diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c
index 515c2d4e639..bfd25366b49 100644
--- a/sys/kern/kern_exit.c
+++ b/sys/kern/kern_exit.c
@@ -195,6 +195,13 @@ proc_clear_orphan(struct proc *p)
 	p->p_treeflag &= ~P_TREE_ORPHANED;
 }
 
+void
+exit_onexit(struct proc *p)
+{
+	MPASS(p->p_numthreads == 1);
+	umtx_thread_exit(FIRST_THREAD_IN_PROC(p));
+}
+
 /*
  * exit -- death of process.
  */
@@ -370,7 +377,6 @@ exit1(struct thread *td, int rval, int signo)
 
 	PROC_UNLOCK(p);
 
-	umtx_thread_exit(td);
 	if (p->p_sysent->sv_onexit != NULL)
 		p->p_sysent->sv_onexit(p);
 	seltdfini(td);
diff --git a/sys/mips/mips/elf_machdep.c b/sys/mips/mips/elf_machdep.c
index 9e27e5e7f2a..8ac07a5b0ac 100644
--- a/sys/mips/mips/elf_machdep.c
+++ b/sys/mips/mips/elf_machdep.c
@@ -89,6 +89,8 @@ static struct sysentvec elf_freebsd_sysvec = {
 	.sv_schedtail	= NULL,
 	.sv_thread_detach = NULL,
 	.sv_trap	= NULL,
+	.sv_onexec_old	= exec_onexec_old,
+	.sv_onexit	= exit_onexit,
 };
 
 static __ElfN(Brandinfo) freebsd_brand_info = {
diff --git a/sys/powerpc/powerpc/elf32_machdep.c b/sys/powerpc/powerpc/elf32_machdep.c
index 04150f02bb9..e98b4c3f08c 100644
--- a/sys/powerpc/powerpc/elf32_machdep.c
+++ b/sys/powerpc/powerpc/elf32_machdep.c
@@ -131,6 +131,8 @@ struct sysentvec elf32_freebsd_sysvec = {
 	.sv_trap	= NULL,
 	.sv_hwcap	= &cpu_features,
 	.sv_hwcap2	= &cpu_features2,
+	.sv_onexec_old	= exec_onexec_old,
+	.sv_onexit	= exit_onexit,
 };
 INIT_SYSENTVEC(elf32_sysvec, &elf32_freebsd_sysvec);
 
diff --git a/sys/powerpc/powerpc/elf64_machdep.c b/sys/powerpc/powerpc/elf64_machdep.c
index 1bca857d9ca..37765381745 100644
--- a/sys/powerpc/powerpc/elf64_machdep.c
+++ b/sys/powerpc/powerpc/elf64_machdep.c
@@ -93,6 +93,8 @@ struct sysentvec elf64_freebsd_sysvec_v1 = {
 	.sv_trap	= NULL,
 	.sv_hwcap	= &cpu_features,
 	.sv_hwcap2	= &cpu_features2,
+	.sv_onexec_old	= exec_onexec_old,
+	.sv_onexit	= exit_onexit,
 };
 
 struct sysentvec elf64_freebsd_sysvec_v2 = {
@@ -129,6 +131,8 @@ struct sysentvec elf64_freebsd_sysvec_v2 = {
 	.sv_trap	= NULL,
 	.sv_hwcap	= &cpu_features,
 	.sv_hwcap2	= &cpu_features2,
+	.sv_onexec_old	= exec_onexec_old,
+	.sv_onexit	= exit_onexit,
 };
 
 static boolean_t ppc64_elfv1_header_match(struct image_params *params,
diff --git a/sys/riscv/riscv/elf_machdep.c b/sys/riscv/riscv/elf_machdep.c
index 06d117128ef..cf479ec6d15 100644
--- a/sys/riscv/riscv/elf_machdep.c
+++ b/sys/riscv/riscv/elf_machdep.c
@@ -96,6 +96,8 @@ struct sysentvec elf64_freebsd_sysvec = {
 	.sv_trap	= NULL,
 	.sv_hwcap	= &elf_hwcap,
 	.sv_machine_arch = riscv_machine_arch,
+	.sv_onexec_old	= exec_onexec_old,
+	.sv_onexit	= exit_onexit,
 };
 INIT_SYSENTVEC(elf64_sysvec, &elf64_freebsd_sysvec);
 
diff --git a/sys/sys/sysent.h b/sys/sys/sysent.h
index ff37806efd9..a6b4b9fe937 100644
--- a/sys/sys/sysent.h
+++ b/sys/sys/sysent.h
@@ -317,6 +317,9 @@ void exec_sysvec_init(void *param);
 void exec_sysvec_init_secondary(struct sysentvec *sv, struct sysentvec *sv2);
 void exec_inittk(void);
 
+void exit_onexit(struct proc *p);
+void exec_onexec_old(struct thread *td);
+
 #define INIT_SYSENTVEC(name, sv)					\
     SYSINIT(name, SI_SUB_EXEC, SI_ORDER_ANY,				\
 	(sysinit_cfunc_t)exec_sysvec_init, sv);