diff --git a/sbin/ifconfig/af_inet6.c b/sbin/ifconfig/af_inet6.c
index 0731238bf9bc..d74b0d21492b 100644
--- a/sbin/ifconfig/af_inet6.c
+++ b/sbin/ifconfig/af_inet6.c
@@ -509,8 +509,6 @@ static struct cmd inet6_cmds[] = {
 	DEF_CMD("-ifdisabled",	-ND6_IFF_IFDISABLED,	setnd6flags),
 	DEF_CMD("nud",		ND6_IFF_PERFORMNUD,	setnd6flags),
 	DEF_CMD("-nud",		-ND6_IFF_PERFORMNUD,	setnd6flags),
-	DEF_CMD("prefer_source",ND6_IFF_PREFER_SOURCE,	setnd6flags),
-	DEF_CMD("-prefer_source",-ND6_IFF_PREFER_SOURCE,setnd6flags),
 	DEF_CMD("auto_linklocal",ND6_IFF_AUTO_LINKLOCAL,setnd6flags),
 	DEF_CMD("-auto_linklocal",-ND6_IFF_AUTO_LINKLOCAL,setnd6flags),
 	DEF_CMD_ARG("pltime",        			setip6pltime),
diff --git a/sbin/ifconfig/ifconfig.8 b/sbin/ifconfig/ifconfig.8
index 44f6c8491e02..f22cc50598ca 100644
--- a/sbin/ifconfig/ifconfig.8
+++ b/sbin/ifconfig/ifconfig.8
@@ -28,7 +28,7 @@
 .\"     From: @(#)ifconfig.8	8.3 (Berkeley) 1/5/94
 .\" $FreeBSD$
 .\"
-.Dd May 27, 2012
+.Dd July 9, 2012
 .Dt IFCONFIG 8
 .Os
 .Sh NAME
@@ -716,12 +716,6 @@ Set a flag to enable Neighbor Unreachability Detection.
 .It Cm -nud
 Clear a flag
 .Cm nud .
-.It Cm prefer_source
-Set a flag to prefer addresses on the interface as candidates of the
-source address for outgoing packets.
-.It Cm -prefer_source
-Clear a flag
-.Cm prefer_source .
 .El
 .Pp
 The following parameters are specific to cloning
diff --git a/sys/netinet6/nd6.h b/sys/netinet6/nd6.h
index c44e7048b8cc..eb0bd44ccda4 100644
--- a/sys/netinet6/nd6.h
+++ b/sys/netinet6/nd6.h
@@ -79,7 +79,7 @@ struct nd_ifinfo {
 
 #define ND6_IFF_PERFORMNUD	0x1
 #define ND6_IFF_ACCEPT_RTADV	0x2
-#define ND6_IFF_PREFER_SOURCE	0x4 /* XXX: not related to ND. */
+#define ND6_IFF_PREFER_SOURCE	0x4 /* Not used in FreeBSD. */
 #define ND6_IFF_IFDISABLED	0x8 /* IPv6 operation is disabled due to
 				     * DAD failure.  (XXX: not ND-specific)
 				     */
diff --git a/usr.sbin/ndp/ndp.8 b/usr.sbin/ndp/ndp.8
index 76f558ca2439..1fb63f815af7 100644
--- a/usr.sbin/ndp/ndp.8
+++ b/usr.sbin/ndp/ndp.8
@@ -29,7 +29,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd September 2, 2009
+.Dd July 9, 2012
 .Dt NDP 8
 .Os
 .\"
@@ -192,15 +192,6 @@ on
 This flag is set by
 .Va net.inet6.ip6.auto_linklocal
 sysctl variable.
-.It Ic prefer_source
-Prefer addresses on the
-.Ar interface
-as candidates of the source address for outgoing packets.
-The default value of this flag is off.
-For more details about the entire algorithm of source address
-selection, see the
-.Pa IMPLEMENTATION
-file supplied with the KAME kit.
 .It Ic disabled
 Disable IPv6 operation on the interface.
 When disabled, the interface discards any IPv6 packets
diff --git a/usr.sbin/ndp/ndp.c b/usr.sbin/ndp/ndp.c
index e245ac2976da..be21d0fc24a3 100644
--- a/usr.sbin/ndp/ndp.c
+++ b/usr.sbin/ndp/ndp.c
@@ -1007,9 +1007,6 @@ ifinfo(ifname, argc, argv)
 #endif
 #ifdef ND6_IFF_AUTO_LINKLOCAL
 		SETFLAG("auto_linklocal", ND6_IFF_AUTO_LINKLOCAL);
-#endif
-#ifdef ND6_IFF_PREFER_SOURCE
-		SETFLAG("prefer_source", ND6_IFF_PREFER_SOURCE);
 #endif
 		SETVALUE("basereachable", ND.basereachable);
 		SETVALUE("retrans", ND.retrans);
@@ -1083,10 +1080,6 @@ ifinfo(ifname, argc, argv)
 #ifdef ND6_IFF_AUTO_LINKLOCAL
 		if ((ND.flags & ND6_IFF_AUTO_LINKLOCAL))
 			printf("auto_linklocal ");
-#endif
-#ifdef ND6_IFF_PREFER_SOURCE
-		if ((ND.flags & ND6_IFF_PREFER_SOURCE))
-			printf("prefer_source ");
 #endif
 	}
 	putc('\n', stdout);