Index: usr.sbin/bhyve/net_backends.h
===================================================================
--- usr.sbin/bhyve/net_backends.h
+++ usr.sbin/bhyve/net_backends.h
@@ -59,6 +59,7 @@
  */
 #define	VIRTIO_NET_F_CSUM	(1 <<  0) /* host handles partial cksum */
 #define	VIRTIO_NET_F_GUEST_CSUM	(1 <<  1) /* guest handles partial cksum */
+#define	VIRTIO_NET_F_MTU	(1 <<  3) /* initial MTU advice */
 #define	VIRTIO_NET_F_MAC	(1 <<  5) /* host supplies MAC */
 #define	VIRTIO_NET_F_GSO_DEPREC	(1 <<  6) /* deprecated: host handles GSO */
 #define	VIRTIO_NET_F_GUEST_TSO4	(1 <<  7) /* guest can rcv TSOv4 */
@@ -76,6 +77,7 @@
 #define	VIRTIO_NET_F_CTRL_VLAN	(1 << 19) /* control channel VLAN filtering */
 #define	VIRTIO_NET_F_GUEST_ANNOUNCE \
 				(1 << 21) /* guest can send gratuitous pkts */
+#define	VIRTIO_NET_F_MQ		(1 << 22) /* host supports multiple VQ pairs */
 
 /*
  * Fixed network header size
Index: usr.sbin/bhyve/net_utils.h
===================================================================
--- usr.sbin/bhyve/net_utils.h
+++ usr.sbin/bhyve/net_utils.h
@@ -35,5 +35,6 @@
 
 void	net_genmac(struct pci_devinst *pi, uint8_t *macaddr);
 int	net_parsemac(char *mac_str, uint8_t *mac_addr);
+int	net_parsemtu(const char *mtu_str, unsigned long *mtu);
 
 #endif /* _NET_UTILS_H_ */
Index: usr.sbin/bhyve/net_utils.c
===================================================================
--- usr.sbin/bhyve/net_utils.c
+++ usr.sbin/bhyve/net_utils.c
@@ -31,9 +31,12 @@
 #include <sys/types.h>
 #include <net/ethernet.h>
 
+#include <assert.h>
 #include <errno.h>
+#include <limits.h>
 #include <md5.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include "bhyverun.h"
@@ -59,6 +62,37 @@
 		memcpy(mac_addr, ea->octet, ETHER_ADDR_LEN);
 
         return (0);
+}
+
+int
+net_parsemtu(const char *mtu_str, unsigned long *mtu)
+{
+	char *end;
+	unsigned long val;
+
+	assert(mtu_str != NULL);
+
+	if (*mtu_str == '-')
+		goto err;
+
+	val = strtoul(mtu_str, &end, 0);
+
+	if (*end != '\0')
+		goto err;
+
+	if (val == ULONG_MAX)
+		return (ERANGE);
+
+	if (val == 0 && errno == EINVAL)
+		return (EINVAL);
+
+	*mtu = val;
+
+	return (0);
+
+err:
+	errno = EINVAL;
+	return (EINVAL);
 }
 
 void
Index: usr.sbin/bhyve/pci_virtio_net.c
===================================================================
--- usr.sbin/bhyve/pci_virtio_net.c
+++ usr.sbin/bhyve/pci_virtio_net.c
@@ -67,6 +67,9 @@
 
 #define VTNET_MAX_PKT_LEN	(65536 + 64)
 
+#define VTNET_MIN_MTU	ETHERMIN
+#define VTNET_MAX_MTU	65535
+
 #define VTNET_S_HOSTCAPS      \
   ( VIRTIO_NET_F_MAC | VIRTIO_NET_F_STATUS | \
     VIRTIO_F_NOTIFY_ON_EMPTY | VIRTIO_RING_F_INDIRECT_DESC)
@@ -77,6 +80,8 @@
 struct virtio_net_config {
 	uint8_t  mac[6];
 	uint16_t status;
+	uint16_t max_virtqueue_pairs;
+	uint16_t mtu;
 } __packed;
 
 /*
@@ -532,6 +537,8 @@
 	struct pci_vtnet_softc *sc;
 	char tname[MAXCOMLEN + 1];
 	int mac_provided;
+	int mtu_provided;
+	unsigned long mtu = ETHERMTU;
 
 	/*
 	 * Allocate data structures for further virtio initializations.
@@ -557,6 +564,7 @@
 	 * if specified.
 	 */
 	mac_provided = 0;
+	mtu_provided = 0;
 	if (opts != NULL) {
 		char *devname;
 		char *vtopts;
@@ -585,6 +593,17 @@
 				if (err)
 					break;
 				mac_provided = 1;
+			} else if (strcmp(key, "mtu") == 0) {
+				err = net_parsemtu(value, &mtu);
+				if (err)
+					break;
+
+				if (mtu < VTNET_MIN_MTU || mtu > VTNET_MAX_MTU) {
+					err = EINVAL;
+					errno = EINVAL;
+					break;
+				}
+				mtu_provided = 1;
 			}
 		}
 
@@ -608,6 +627,17 @@
 	if (!mac_provided) {
 		net_genmac(pi, sc->vsc_config.mac);
 	}
+
+	sc->vsc_config.mtu = mtu;
+	if (mtu_provided) {
+		sc->vsc_consts.vc_hv_caps |= VIRTIO_NET_F_MTU;
+	}
+
+	/* 
+	 * Since we do not actually support multiqueue,
+	 * set the maximum virtqueue pairs to 1. 
+	 */
+	sc->vsc_config.max_virtqueue_pairs = 1;
 
 	/* initialize config space */
 	pci_set_cfgdata16(pi, PCIR_DEVICE, VIRTIO_DEV_NET);