Index: sys/kern/kern_fork.c
===================================================================
--- sys/kern/kern_fork.c
+++ sys/kern/kern_fork.c
@@ -735,6 +735,7 @@
 	if (fr->fr_flags & RFPPWAIT) {
 		td->td_pflags |= TDP_RFPPWAIT;
 		td->td_rfppwait_p = p2;
+		td->td_dbgflags |= TDB_VFORK;
 	}
 	PROC_UNLOCK(p2);
 
Index: sys/kern/subr_syscall.c
===================================================================
--- sys/kern/subr_syscall.c
+++ sys/kern/subr_syscall.c
@@ -242,5 +242,13 @@
 			cv_timedwait(&p2->p_pwait, &p2->p_mtx, hz);
 		}
 		PROC_UNLOCK(p2);
+
+		if (td->td_dbgflags & TDB_VFORK) {
+			PROC_LOCK(p);
+			if (p->p_ptevents & PTRACE_VFORK)
+				ptracestop(td, SIGTRAP);
+			td->td_dbgflags &= ~TDB_VFORK;
+			PROC_UNLOCK(p);
+		}
 	}
 }
Index: sys/kern/sys_process.c
===================================================================
--- sys/kern/sys_process.c
+++ sys/kern/sys_process.c
@@ -1295,7 +1295,11 @@
 		if (td2->td_dbgflags & TDB_FORK) {
 			pl->pl_flags |= PL_FLAG_FORKED;
 			pl->pl_child_pid = td2->td_dbg_forked;
-		}
+			if (td2->td_dbgflags & TDB_VFORK)
+				pl->pl_flags |= PL_FLAG_VFORKED;
+		} else if ((td2->td_dbgflags & (TDB_SCX | TDB_VFORK)) ==
+		    TDB_VFORK)
+			pl->pl_flags |= PL_FLAG_VFORK_DONE;
 		if (td2->td_dbgflags & TDB_CHILD)
 			pl->pl_flags |= PL_FLAG_CHILD;
 		if (td2->td_dbgflags & TDB_BORN)
Index: sys/sys/proc.h
===================================================================
--- sys/sys/proc.h
+++ sys/sys/proc.h
@@ -418,6 +418,7 @@
 #define	TDB_CHILD	0x00000100 /* New child indicator for ptrace() */
 #define	TDB_BORN	0x00000200 /* New LWP indicator for ptrace() */
 #define	TDB_EXIT	0x00000400 /* Exiting LWP indicator for ptrace() */
+#define	TDB_VFORK	0x00000800 /* vfork indicator for ptrace() */
 
 /*
  * "Private" flags kept in td_pflags:
Index: sys/sys/ptrace.h
===================================================================
--- sys/sys/ptrace.h
+++ sys/sys/ptrace.h
@@ -90,6 +90,7 @@
 #define	PTRACE_SYSCALL	(PTRACE_SCE | PTRACE_SCX)
 #define	PTRACE_FORK	0x0010
 #define	PTRACE_LWP	0x0020
+#define	PTRACE_VFORK	0x0040
 
 #define	PTRACE_DEFAULT	(PTRACE_EXEC | PTRACE_SIG)
 
@@ -125,6 +126,8 @@
 #define	PL_FLAG_CHILD	0x80	/* I am from child */
 #define	PL_FLAG_BORN	0x100	/* new LWP */
 #define	PL_FLAG_EXITED	0x200	/* exiting LWP */
+#define	PL_FLAG_VFORKED	0x400	/* new child via vfork */
+#define	PL_FLAG_VFORK_DONE 0x800 /* vfork parent has resumed */
 	sigset_t	pl_sigmask;	/* LWP signal mask */
 	sigset_t	pl_siglist;	/* LWP pending signal */
 	struct __siginfo pl_siginfo;	/* siginfo for signal */
Index: tests/sys/kern/ptrace_test.c
===================================================================
--- tests/sys/kern/ptrace_test.c
+++ tests/sys/kern/ptrace_test.c
@@ -1587,6 +1587,130 @@
 	ATF_REQUIRE(errno == ECHILD);
 }
 
+/*
+ * Verify that the expected ptrace events are reported for PTRACE_VFORK.
+ */
+ATF_TC_WITHOUT_HEAD(ptrace__ptrace_vfork);
+ATF_TC_BODY(ptrace__ptrace_vfork, tc)
+{
+	struct ptrace_lwpinfo pl;
+	pid_t fpid, wpid;
+	int events, status;
+
+	ATF_REQUIRE((fpid = fork()) != -1);
+	if (fpid == 0) {
+		trace_me();
+		follow_fork_parent(true);
+	}
+
+	/* The first wait() should report the stop from SIGSTOP. */
+	wpid = waitpid(fpid, &status, 0);
+	ATF_REQUIRE(wpid == fpid);
+	ATF_REQUIRE(WIFSTOPPED(status));
+	ATF_REQUIRE(WSTOPSIG(status) == SIGSTOP);
+
+	ATF_REQUIRE(ptrace(PT_GET_EVENT_MASK, fpid, (caddr_t)&events,
+	    sizeof(events)) == 0);
+	events |= PTRACE_VFORK;
+	ATF_REQUIRE(ptrace(PT_SET_EVENT_MASK, fpid, (caddr_t)&events,
+	    sizeof(events)) == 0);
+	
+	/* Continue the child ignoring the SIGSTOP. */
+	ATF_REQUIRE(ptrace(PT_CONTINUE, fpid, (caddr_t)1, 0) != -1);
+
+	/* The next event should report the end of the vfork. */
+	wpid = wait(&status);
+	ATF_REQUIRE(wpid == fpid);
+	ATF_REQUIRE(WIFSTOPPED(status));
+	ATF_REQUIRE(WSTOPSIG(status) == SIGTRAP);
+	ATF_REQUIRE(ptrace(PT_LWPINFO, wpid, (caddr_t)&pl, sizeof(pl)) != -1);
+	ATF_REQUIRE((pl.pl_flags & PL_FLAG_VFORK_DONE) != 0);
+
+	ATF_REQUIRE(ptrace(PT_CONTINUE, fpid, (caddr_t)1, 0) != -1);
+
+	wpid = wait(&status);
+	ATF_REQUIRE(wpid == fpid);
+	ATF_REQUIRE(WIFEXITED(status));
+	ATF_REQUIRE(WEXITSTATUS(status) == 1);
+
+	wpid = wait(&status);
+	ATF_REQUIRE(wpid == -1);
+	ATF_REQUIRE(errno == ECHILD);
+}
+
+ATF_TC_WITHOUT_HEAD(ptrace__ptrace_vfork_follow);
+ATF_TC_BODY(ptrace__ptrace_vfork_follow, tc)
+{
+	struct ptrace_lwpinfo pl[2];
+	pid_t children[2], fpid, wpid;
+	int events, status;
+
+	ATF_REQUIRE((fpid = fork()) != -1);
+	if (fpid == 0) {
+		trace_me();
+		follow_fork_parent(true);
+	}
+
+	/* Parent process. */
+	children[0] = fpid;
+
+	/* The first wait() should report the stop from SIGSTOP. */
+	wpid = waitpid(children[0], &status, 0);
+	ATF_REQUIRE(wpid == children[0]);
+	ATF_REQUIRE(WIFSTOPPED(status));
+	ATF_REQUIRE(WSTOPSIG(status) == SIGSTOP);
+
+	ATF_REQUIRE(ptrace(PT_GET_EVENT_MASK, children[0], (caddr_t)&events,
+	    sizeof(events)) == 0);
+	events |= PTRACE_FORK | PTRACE_VFORK;
+	ATF_REQUIRE(ptrace(PT_SET_EVENT_MASK, children[0], (caddr_t)&events,
+	    sizeof(events)) == 0);
+
+	/* Continue the child ignoring the SIGSTOP. */
+	ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1);
+
+	/* Wait for both halves of the fork event to get reported. */
+	children[1] = handle_fork_events(children[0], pl);
+	ATF_REQUIRE(children[1] > 0);
+
+	ATF_REQUIRE((pl[0].pl_flags & PL_FLAG_VFORKED) != 0);
+
+	ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1);
+	ATF_REQUIRE(ptrace(PT_CONTINUE, children[1], (caddr_t)1, 0) != -1);
+
+	/*
+	 * The child can't exit until the grandchild reports status, so the
+	 * grandchild should report its exit first to the debugger.
+	 */
+	wpid = waitpid(children[1], &status, 0);
+	ATF_REQUIRE(wpid == children[1]);
+	ATF_REQUIRE(WIFEXITED(status));
+	ATF_REQUIRE(WEXITSTATUS(status) == 2);
+
+	/*
+	 * The child should report it's vfork() completion before it
+	 * exits.
+	 */
+	wpid = wait(&status);
+	ATF_REQUIRE(wpid == children[0]);
+	ATF_REQUIRE(WIFSTOPPED(status));
+	ATF_REQUIRE(WSTOPSIG(status) == SIGTRAP);
+	ATF_REQUIRE(ptrace(PT_LWPINFO, wpid, (caddr_t)&pl[0], sizeof(pl[0])) !=
+	    -1);
+	ATF_REQUIRE((pl[0].pl_flags & PL_FLAG_VFORK_DONE) != 0);
+
+	ATF_REQUIRE(ptrace(PT_CONTINUE, children[0], (caddr_t)1, 0) != -1);
+
+	wpid = wait(&status);
+	ATF_REQUIRE(wpid == children[0]);
+	ATF_REQUIRE(WIFEXITED(status));
+	ATF_REQUIRE(WEXITSTATUS(status) == 1);
+
+	wpid = wait(&status);
+	ATF_REQUIRE(wpid == -1);
+	ATF_REQUIRE(errno == ECHILD);
+}
+
 ATF_TP_ADD_TCS(tp)
 {
 
@@ -1613,6 +1737,8 @@
 	ATF_TP_ADD_TC(tp, ptrace__ptrace_sig_disable);
 	ATF_TP_ADD_TC(tp, ptrace__ptrace_sig_enable);
 	ATF_TP_ADD_TC(tp, ptrace__event_mask);
+	ATF_TP_ADD_TC(tp, ptrace__ptrace_vfork);
+	ATF_TP_ADD_TC(tp, ptrace__ptrace_vfork_follow);
 
 	return (atf_no_error());
 }