Index: src/sys/netinet/tcp_input.c
===================================================================
--- src/sys/netinet/tcp_input.c	(revision 177)
+++ src/sys/netinet/tcp_input.c	(working copy)
@@ -158,6 +158,9 @@
 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD,
 	   &tcp_reass_overflows, 0,
 	   "Global number of TCP Segment Reassembly Queue Overflows");
+int tcp_ts_perconn = 0;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, ts_perconn, CTLFLAG_RW,
+	   &tcp_ts_perconn, 0, "Per connection TCP timestamps");
 
 struct inpcbhead tcb;
 #define	tcb6	tcb  /* for KAME src sync over BSD*'s */
@@ -1091,7 +1094,7 @@
 		if (to.to_flags & TOF_TS) {
 			tp->t_flags |= TF_RCVD_TSTMP;
 			tp->ts_recent = to.to_tsval;
-			tp->ts_recent_age = ticks;
+			tp->ts_recent_age = TCP_TIMESTAMP(tp);
 		}
 		if (to.to_flags & TOF_MSS)
 			tcp_mss(tp, to.to_mss);
@@ -1142,7 +1145,7 @@
 		 */
 		if ((to.to_flags & TOF_TS) != 0 &&
 		    SEQ_LEQ(th->th_seq, tp->last_ack_sent)) {
-			tp->ts_recent_age = ticks;
+			tp->ts_recent_age = TCP_TIMESTAMP(tp);
 			tp->ts_recent = to.to_tsval;
 		}
 
@@ -1187,8 +1190,8 @@
 				 */
 				if ((to.to_flags & TOF_TS) != 0 &&
 				    to.to_tsecr) {
-					tcp_xmit_timer(tp,
-					    ticks - to.to_tsecr + 1);
+					tcp_xmit_timer(tp, TCP_TIMESTAMP(tp) -
+					     to.to_tsecr + 1);
 				} else if (tp->t_rtttime &&
 					    SEQ_GT(th->th_ack, tp->t_rtseq)) {
 					tcp_xmit_timer(tp,
@@ -1575,7 +1578,8 @@
 	    TSTMP_LT(to.to_tsval, tp->ts_recent)) {
 
 		/* Check to see if ts_recent is over 24 days old.  */
-		if ((int)(ticks - tp->ts_recent_age) > TCP_PAWS_IDLE) {
+		if ((int)(TCP_TIMESTAMP(tp) - tp->ts_recent_age) >
+		    TCP_PAWS_IDLE) {
 			/*
 			 * Invalidate ts_recent.  If this segment updates
 			 * ts_recent, the age will be reset later and ts_recent
@@ -1735,7 +1739,7 @@
 	    SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
 	    SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen +
 		((thflags & (TH_SYN|TH_FIN)) != 0))) {
-		tp->ts_recent_age = ticks;
+		tp->ts_recent_age = TCP_TIMESTAMP(tp);
 		tp->ts_recent = to.to_tsval;
 	}
 
@@ -2071,7 +2075,7 @@
 		 */
 		if ((to.to_flags & TOF_TS) != 0 &&
 		    to.to_tsecr) {
-			tcp_xmit_timer(tp, ticks - to.to_tsecr + 1);
+			tcp_xmit_timer(tp, TCP_TIMESTAMP(tp) - to.to_tsecr + 1);
 		} else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) {
 			tcp_xmit_timer(tp, ticks - tp->t_rtttime);
 		}
@@ -2617,7 +2621,8 @@
 			 * If echoed timestamp is later than the current time,
 			 * fall back to non RFC1323 RTT calculation.
 			 */
-			if ((to->to_tsecr != 0) && TSTMP_GT(to->to_tsecr, ticks))
+			if ((to->to_tsecr != 0) && TSTMP_GT(to->to_tsecr,
+			    TCP_TIMESTAMP(tp)))
 				to->to_tsecr = 0;
 			break;
 #ifdef TCP_SIGNATURE
Index: src/sys/netinet/tcp_subr.c
===================================================================
--- src/sys/netinet/tcp_subr.c	(revision 177)
+++ src/sys/netinet/tcp_subr.c	(working copy)
@@ -622,6 +622,7 @@
 	tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 	tp->t_rcvtime = ticks;
 	tp->t_bw_rtttime = ticks;
+	tp->ts_timebase = ticks;
 	/*
 	 * IPv4 TTL initialization is necessary for an IPv6 socket as well,
 	 * because the socket may be bound to an IPv6 wildcard address,
@@ -1693,10 +1694,13 @@
 	 * Set t_recent if timestamps are used on the connection.
 	 */
 	if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) ==
-	    (TF_REQ_TSTMP|TF_RCVD_TSTMP))
+	    (TF_REQ_TSTMP|TF_RCVD_TSTMP)) {
 		tw->t_recent = tp->ts_recent;
-	else
+		tw->t_timebase = tp->ts_timebase;
+	} else {
 		tw->t_recent = 0;
+		tw->t_timebase = 0;
+	}
 
 	tw->snd_nxt = tp->snd_nxt;
 	tw->rcv_nxt = tp->rcv_nxt;
@@ -1841,7 +1845,7 @@
 
 		/* Form timestamp option as shown in appendix A of RFC 1323. */
 		*lp++ = htonl(TCPOPT_TSTAMP_HDR);
-		*lp++ = htonl(ticks);
+		*lp++ = htonl(ticks - tw->t_timebase);
 		*lp   = htonl(tw->t_recent);
 		optp += TCPOLEN_TSTAMP_APPA;
 	}
Index: src/sys/netinet/tcp_var.h
===================================================================
--- src/sys/netinet/tcp_var.h	(revision 177)
+++ src/sys/netinet/tcp_var.h	(working copy)
@@ -50,6 +50,7 @@
 LIST_HEAD(tsegqe_head, tseg_qent);
 extern int	tcp_reass_qsize;
 extern struct uma_zone *tcp_reass_zone;
+extern int	tcp_ts_perconn;
 
 struct sackblk {
 	tcp_seq start;		/* start seq no. of sack block */
@@ -175,6 +176,7 @@
 	u_char	request_r_scale;	/* pending window scaling */
 	u_char	requested_s_scale;
 	u_long	ts_recent;		/* timestamp echo data */
+	u_long	ts_timebase;		/* our time base */
 
 	u_long	ts_recent_age;		/* when last updated */
 	tcp_seq	last_ack_sent;
@@ -220,6 +222,8 @@
 #define	TCP_SIG_SPI	0x1000
 #endif /* TCP_SIGNATURE */
 
+#define	TCP_TIMESTAMP(tp) (tcp_ts_perconn ? (ticks - (tp)->ts_timebase) : ticks)
+
 /*
  * Structure to hold TCP options that are only used during segment
  * processing (in tcp_input), but not held in the tcpcb.
@@ -297,6 +301,7 @@
 	u_short		tw_so_options;	/* copy of so_options */
 	struct ucred	*tw_cred;	/* user credentials */
 	u_long		t_recent;
+	u_long		t_timebase;
 	u_long		t_starttime;
 	int		tw_time;
 	LIST_ENTRY(tcptw) tw_2msl;
Index: src/sys/netinet/tcp_output.c
===================================================================
--- src/sys/netinet/tcp_output.c	(revision 177)
+++ src/sys/netinet/tcp_output.c	(working copy)
@@ -571,7 +571,7 @@
 
 		/* Form timestamp option as shown in appendix A of RFC 1323. */
 		*lp++ = htonl(TCPOPT_TSTAMP_HDR);
-		*lp++ = htonl(ticks);
+		*lp++ = htonl(TCP_TIMESTAMP(tp));
 		*lp   = htonl(tp->ts_recent);
 		optlen += TCPOLEN_TSTAMP_APPA;
 	}
Index: src/sys/netinet/tcp_syncache.c
===================================================================
--- src/sys/netinet/tcp_syncache.c	(revision 177)
+++ src/sys/netinet/tcp_syncache.c	(working copy)
@@ -278,7 +278,7 @@
 		 * The bucket is full, toss the oldest element.
 		 */
 		sc2 = TAILQ_FIRST(&sch->sch_bucket);
-		sc2->sc_tp->ts_recent = ticks;
+		sc2->sc_tp->ts_recent = TCP_TIMESTAMP(sc2->sc_tp);
 		syncache_drop(sc2, sch);
 		tcpstat.tcps_sc_bucketoverflow++;
 	} else if (tcp_syncache.cache_count >= tcp_syncache.cache_limit) {
@@ -293,7 +293,7 @@
 			if (sc2 != NULL)
 				break;
 		}
-		sc2->sc_tp->ts_recent = ticks;
+		sc2->sc_tp->ts_recent = TCP_TIMESTAMP(sc2->sc_tp);
 		syncache_drop(sc2, NULL);
 		tcpstat.tcps_sc_cacheoverflow++;
 	}
@@ -688,7 +688,7 @@
 	if (sc->sc_flags & SCF_TIMESTAMP) {
 		tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP;
 		tp->ts_recent = sc->sc_tsrecent;
-		tp->ts_recent_age = ticks;
+		tp->ts_recent_age = TCP_TIMESTAMP(tp);
 	}
 #ifdef TCP_SIGNATURE
 	if (sc->sc_flags & SCF_SIGNATURE)
@@ -892,7 +892,7 @@
 			if (sc != NULL)
 				break;
 		}
-		sc->sc_tp->ts_recent = ticks;
+		sc->sc_tp->ts_recent = TCP_TIMESTAMP(sc->sc_tp);
 		syncache_drop(sc, NULL);
 		tcpstat.tcps_sc_zonefail++;
 		sc = uma_zalloc(tcp_syncache.zone, M_NOWAIT);
@@ -1156,9 +1156,12 @@
 		if (sc->sc_flags & SCF_TIMESTAMP) {
 			u_int32_t *lp = (u_int32_t *)(optp);
 
+			/* Reset the time base */
+			sc->sc_tp->ts_timebase = ticks;
+
 			/* Form timestamp option per appendix A of RFC 1323. */
 			*lp++ = htonl(TCPOPT_TSTAMP_HDR);
-			*lp++ = htonl(ticks);
+			*lp++ = htonl(TCP_TIMESTAMP(sc->sc_tp));
 			*lp   = htonl(sc->sc_tsrecent);
 			optp += TCPOLEN_TSTAMP_APPA;
 		}