Index: sys/netinet/tcp_stacks/rack.c
===================================================================
--- sys/netinet/tcp_stacks/rack.c
+++ sys/netinet/tcp_stacks/rack.c
@@ -12508,6 +12508,7 @@
 				  ip6, rack->r_ctl.fsb.th);
 	} else
 #endif				/* INET6 */
+#ifdef INET
 	{
 		rack->r_ctl.fsb.tcp_ip_hdr_len = sizeof(struct tcpiphdr);
 		ip = (struct ip *)rack->r_ctl.fsb.tcp_ip_hdr;
@@ -12527,9 +12528,40 @@
 				  tp->t_port,
 				  ip, rack->r_ctl.fsb.th);
 	}
+#endif
 	rack->r_fsb_inited = 1;
 }
 
+static void
+rack_dscp_change(struct tcpcb *tp)
+{
+#ifdef INET6
+	struct ip6_hdr *ip6 = NULL;
+#endif
+#ifdef INET
+	struct ip *ip = NULL;
+#endif
+	struct tcp_rack *rack;
+	/*
+	 * A socket option changed the outgoing TOS/TCLASS update
+	 * the fast send block.
+	 */
+	rack = (struct tcp_rack *)tp->t_fb_ptr;
+#ifdef INET6
+	if (rack->r_is_v6) {
+		ip6 = (struct ip6_hdr *)rack->r_ctl.fsb.tcp_ip_hdr;
+		ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) |
+			(rack->rc_inp->inp_flow & IPV6_FLOWINFO_MASK);
+	}
+#endif
+#ifdef INET
+	else {
+		ip = (struct ip *)rack->r_ctl.fsb.tcp_ip_hdr;
+		ip->ip_tos = rack->rc_inp->inp_ip_tos;
+	}
+#endif
+}
+
 static int
 rack_init_fsb(struct tcpcb *tp, struct tcp_rack *rack)
 {
@@ -20232,6 +20264,7 @@
 	.tfb_tcp_mtu_chg = rack_mtu_change,
 	.tfb_pru_options = rack_pru_options,
 	.tfb_hwtls_change = rack_hw_tls_change,
+	.tfb_dscp_change = rack_dscp_change,
 };
 
 /*
Index: sys/netinet/tcp_subr.c
===================================================================
--- sys/netinet/tcp_subr.c
+++ sys/netinet/tcp_subr.c
@@ -4129,3 +4129,4 @@
 		}
 	}
 }
+
Index: sys/netinet/tcp_usrreq.c
===================================================================
--- sys/netinet/tcp_usrreq.c
+++ sys/netinet/tcp_usrreq.c
@@ -1745,6 +1745,29 @@
 #ifdef INET6
 		if (inp->inp_vflag & INP_IPV6PROTO) {
 			error = ip6_ctloutput(so, sopt);
+			/*
+			 * If the TCLASS changes we need to 
+			 * notify tcp stacks that care.
+			 */
+			if ((sopt->sopt_level == IPPROTO_IPV6) &&
+			    (sopt->sopt_name == IPV6_TCLASS) &&
+			    (error == 0)) {
+				INP_WLOCK(inp);
+				if ((inp->inp_flags &
+				    (INP_TIMEWAIT | INP_DROPPED))) {
+					INP_WUNLOCK(inp);
+					return (ECONNRESET);
+				}
+				tp = intotcpcb(inp);
+				if (tp->t_fb->tfb_dscp_change != NULL) {
+					/*
+					 * This stack wants to know about DSCP codepoint
+					 * changes.
+					 */
+					(tp->t_fb->tfb_dscp_change)(tp);
+				}
+				INP_WUNLOCK(inp);
+			}
 			/*
 			 * In case of the IPV6_USE_MIN_MTU socket option,
 			 * the INC_IPV6MINMTU flag to announce a corresponding
@@ -1788,7 +1811,30 @@
 #endif
 #ifdef INET
 		{
+			/*
+			 * If the TOS changes we need to 
+			 * notify tcp stacks that care.
+			 */
 			error = ip_ctloutput(so, sopt);
+			if ((sopt->sopt_level == IPPROTO_IP) &&
+			    (sopt->sopt_name == IP_TOS) &&
+			    (error == 0)) {
+				INP_WLOCK(inp);
+				if ((inp->inp_flags &
+				    (INP_TIMEWAIT | INP_DROPPED))) {
+					INP_WUNLOCK(inp);
+					return (ECONNRESET);
+				}
+				tp = intotcpcb(inp);
+				if (tp->t_fb->tfb_dscp_change != NULL) {
+					/*
+					 * This stack wants to know about DSCP codepoint
+					 * changes.
+					 */
+					(tp->t_fb->tfb_dscp_change)(tp);
+				}
+				INP_WUNLOCK(inp);
+			}
 		}
 #endif
 		return (error);
Index: sys/netinet/tcp_var.h
===================================================================
--- sys/netinet/tcp_var.h
+++ sys/netinet/tcp_var.h
@@ -373,6 +373,7 @@
 	void	(*tfb_tcp_mtu_chg)(struct tcpcb *);
 	int	(*tfb_pru_options)(struct tcpcb *, int);
 	void	(*tfb_hwtls_change)(struct tcpcb *, int);
+	void	(*tfb_dscp_change)(struct tcpcb *);
 	volatile uint32_t tfb_refcnt;
 	uint32_t  tfb_flags;
 	uint8_t	tfb_id;