diff --git a/sys/netinet6/in6.c b/sys/netinet6/in6.c
index 9e8e5cd12475..9558d1ba8a1d 100644
--- a/sys/netinet6/in6.c
+++ b/sys/netinet6/in6.c
@@ -652,8 +652,32 @@ in6_control(struct socket *so, u_long cmd, caddr_t data,
 		 * that is, this address might make other addresses detached.
 		 */
 		pfxlist_onlink_check();
-		if (error == 0 && ia)
+		if (error == 0 && ia) {
+			if (ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED) {
+				/*
+				 * Try to clear the flag when a new
+				 * IPv6 address is added onto an
+				 * IFDISABLED interface and it
+				 * succeeds.
+				 */
+				struct in6_ndireq nd;
+
+				memset(&nd, 0, sizeof(nd));
+				nd.ndi.flags = ND_IFINFO(ifp)->flags;
+				nd.ndi.flags &= ~ND6_IFF_IFDISABLED;
+				if (nd6_ioctl(SIOCSIFINFO_FLAGS,
+				    (caddr_t)&nd, ifp) < 0)
+					log(LOG_NOTICE, "SIOCAIFADDR_IN6: "
+					    "SIOCSIFINFO_FLAGS for -ifdisabled "
+					    "failed.");
+				/*
+				 * Ignore failure of clearing the flag
+				 * intentionally.  The failure means
+				 * address duplication was detected.
+				 */
+			}
 			EVENTHANDLER_INVOKE(ifaddr_event, ifp);
+		}
 		break;
 	}
 
diff --git a/sys/netinet6/nd6.c b/sys/netinet6/nd6.c
index b17b5dad1c03..231ce94ecbe3 100644
--- a/sys/netinet6/nd6.c
+++ b/sys/netinet6/nd6.c
@@ -1322,6 +1322,15 @@ nd6_ioctl(u_long cmd, caddr_t data, struct ifnet *ifp)
 		struct ifaddr *ifa;
 		struct in6_ifaddr *ia;
 
+		/*
+		 * Try to clear ifdisabled flag when enabling
+		 * accept_rtadv or auto_linklocal.
+		 */
+		if ((ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED) &&
+		    (ND.flags & (ND6_IFF_ACCEPT_RTADV |
+		    ND6_IFF_AUTO_LINKLOCAL)))
+			ND.flags &= ~ND6_IFF_IFDISABLED;
+
 		if ((ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED) &&
 		    !(ND.flags & ND6_IFF_IFDISABLED)) {
 			/* ifdisabled 1->0 transision */
@@ -1379,6 +1388,27 @@ nd6_ioctl(u_long cmd, caddr_t data, struct ifnet *ifp)
 			/* If no link-local address on ifp, configure */
 			ND_IFINFO(ifp)->flags |= ND6_IFF_AUTO_LINKLOCAL;
 			in6_ifattach(ifp, NULL);
+		} else if (ND_IFINFO(ifp)->flags & ND6_IFF_AUTO_LINKLOCAL) {
+			/*
+			 * When the IF already has
+			 * ND6_IFF_AUTO_LINKLOCAL and no link-local
+			 * address is assigned, try to assign one.
+			 */
+			int haslinklocal = 0;
+			
+			IF_ADDR_LOCK(ifp);
+			TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
+				if (ifa->ifa_addr->sa_family != AF_INET6)
+					continue;
+				ia = (struct in6_ifaddr *)ifa;
+				if (IN6_IS_ADDR_LINKLOCAL(IA6_IN6(ia))) {
+					haslinklocal = 1;
+					break;
+				}
+			}
+			IF_ADDR_UNLOCK(ifp);
+			if (!haslinklocal)
+				in6_ifattach(ifp, NULL);
 		}
 	}
 		ND_IFINFO(ifp)->flags = ND.flags;