Index: sys/netinet6/in6.c
===================================================================
--- sys/netinet6/in6.c
+++ sys/netinet6/in6.c
@@ -649,6 +649,8 @@
 		if (ia->ia6_ndpr == NULL) {
 			ia->ia6_ndpr = pr;
 			pr->ndpr_addrcnt++;
+			if (ia->ia6_flags & IN6_IFF_AUTOCONF)
+				pr->ndpr_num_autoconf_addrs++;
 
 			/*
 			 * If this is the first autoconf address from the
@@ -1355,6 +1357,8 @@
 		    "%s has no prefix\n", ip6_sprintf(ip6buf, IA6_IN6(ia))));
 	} else {
 		ia->ia6_ndpr->ndpr_addrcnt--;
+		if (ia->ia6_flags & IN6_IFF_AUTOCONF)
+			ia->ia6_ndpr->ndpr_num_autoconf_addrs--;
 		/* Do not delete lles within prefix if refcont != 0 */
 		if (ia->ia6_ndpr->ndpr_addrcnt == 0)
 			remove_lle = 1;
Index: sys/netinet6/nd6.h
===================================================================
--- sys/netinet6/nd6.h
+++ sys/netinet6/nd6.h
@@ -237,6 +237,7 @@
 	LIST_HEAD(pr_rtrhead, nd_pfxrouter) ndpr_advrtrs;
 	u_char	ndpr_plen;
 	int	ndpr_addrcnt;	/* count of derived addresses */
+	int	ndpr_num_autoconf_addrs;	/* count of derived addresses, related to autoconf */
 	volatile u_int ndpr_refcnt;
 };
 
Index: sys/netinet6/nd6.c
===================================================================
--- sys/netinet6/nd6.c
+++ sys/netinet6/nd6.c
@@ -1782,7 +1782,8 @@
 
 		ND6_WLOCK();
 		LIST_FOREACH_SAFE(pr, &V_nd_prefix, ndpr_entry, next) {
-			if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr))
+			if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr)
+			    || (pr->ndpr_num_autoconf_addrs != pr->ndpr_addrcnt))
 				continue; /* XXX */
 			nd6_prefix_unlink(pr, &prl);
 		}
Index: sys/netinet6/nd6_rtr.c
===================================================================
--- sys/netinet6/nd6_rtr.c
+++ sys/netinet6/nd6_rtr.c
@@ -1349,6 +1349,7 @@
 	if (new == NULL)
 		return (ENOMEM);
 	refcount_init(&new->ndpr_refcnt, newp != NULL ? 2 : 1);
+	new->ndpr_num_autoconf_addrs = 0;
 	new->ndpr_ifp = pr->ndpr_ifp;
 	new->ndpr_prefix = pr->ndpr_prefix;
 	new->ndpr_plen = pr->ndpr_plen;
@@ -1741,6 +1742,8 @@
 			 * note that we should use pr (not new) for reference.
 			 */
 			pr->ndpr_addrcnt++;
+			if (ia6->ia6_flags & IN6_IFF_AUTOCONF)
+				pr->ndpr_num_autoconf_addrs++;
 			ia6->ia6_ndpr = pr;
 
 			/*
@@ -2378,6 +2381,8 @@
 	}
 	newia->ia6_ndpr = ia0->ia6_ndpr;
 	newia->ia6_ndpr->ndpr_addrcnt++;
+	if (ifra.ifra_flags & IN6_IFF_AUTOCONF)
+		newia->ia6_ndpr->ndpr_num_autoconf_addrs++;
 	ifa_free(&newia->ia_ifa);
 
 	/*