diff --git a/sys/dev/cxgbe/offload.h b/sys/dev/cxgbe/offload.h
index 363423b80fd..bef5f388447 100644
--- a/sys/dev/cxgbe/offload.h
+++ b/sys/dev/cxgbe/offload.h
@@ -144,6 +144,7 @@ struct uld_info {
 };
 
 struct tom_tunables {
+	int cong_algorithm;
 	int sndbuf;
 	int ddp;
 	int rx_coalesce;
diff --git a/sys/dev/cxgbe/t4_main.c b/sys/dev/cxgbe/t4_main.c
index 8b9df4889af..e1bbca38155 100644
--- a/sys/dev/cxgbe/t4_main.c
+++ b/sys/dev/cxgbe/t4_main.c
@@ -5416,6 +5416,12 @@ t4_sysctls(struct adapter *sc)
 		    NULL, "TOE parameters");
 		children = SYSCTL_CHILDREN(oid);
 
+		sc->tt.cong_algorithm = -1;
+		SYSCTL_ADD_INT(ctx, children, OID_AUTO, "cong_algorithm",
+		    CTLFLAG_RW, &sc->tt.cong_algorithm, 0, "congestion control "
+		    "(-1 = default, 0 = reno, 1 = tahoe, 2 = newreno, "
+		    "3 = highspeed)");
+
 		sc->tt.sndbuf = 256 * 1024;
 		SYSCTL_ADD_INT(ctx, children, OID_AUTO, "sndbuf", CTLFLAG_RW,
 		    &sc->tt.sndbuf, 0, "max hardware send buffer size");
diff --git a/sys/dev/cxgbe/tom/t4_connect.c b/sys/dev/cxgbe/tom/t4_connect.c
index f23ba55a24e..b1acd5a58be 100644
--- a/sys/dev/cxgbe/tom/t4_connect.c
+++ b/sys/dev/cxgbe/tom/t4_connect.c
@@ -259,6 +259,9 @@ calc_opt2a(struct socket *so, struct toepcb *toep)
 	if (sc->tt.rx_coalesce)
 		opt2 |= V_RX_COALESCE(M_RX_COALESCE);
 
+	if (sc->tt.cong_algorithm != -1)
+		opt2 |= V_CONG_CNTRL(sc->tt.cong_algorithm & M_CONG_CNTRL);
+
 #ifdef USE_DDP_RX_FLOW_CONTROL
 	if (toep->ulp_mode == ULP_MODE_TCPDDP)
 		opt2 |= F_RX_FC_VALID | F_RX_FC_DDP;
diff --git a/sys/dev/cxgbe/tom/t4_listen.c b/sys/dev/cxgbe/tom/t4_listen.c
index 59d8750c171..09532c26edb 100644
--- a/sys/dev/cxgbe/tom/t4_listen.c
+++ b/sys/dev/cxgbe/tom/t4_listen.c
@@ -1047,6 +1047,9 @@ calc_opt2p(struct adapter *sc, struct port_info *pi, int rxqid,
 	if (sc->tt.rx_coalesce)
 		opt2 |= V_RX_COALESCE(M_RX_COALESCE);
 
+	if (sc->tt.cong_algorithm != -1)
+		opt2 |= V_CONG_CNTRL(sc->tt.cong_algorithm & M_CONG_CNTRL);
+
 #ifdef USE_DDP_RX_FLOW_CONTROL
 	if (ulp_mode == ULP_MODE_TCPDDP)
 		opt2 |= F_RX_FC_VALID | F_RX_FC_DDP;