diff --git a/sys/fs/nfs/nfs_var.h b/sys/fs/nfs/nfs_var.h
index 28088c12d7e..145cbf98446 100644
--- a/sys/fs/nfs/nfs_var.h
+++ b/sys/fs/nfs/nfs_var.h
@@ -609,6 +609,7 @@ int nfscl_relbytelock(vnode_t, u_int64_t, u_int64_t,
 int nfscl_checkwritelocked(vnode_t, struct flock *,
     struct ucred *, NFSPROC_T *, void *, int);
 void nfscl_lockrelease(struct nfscllockowner *, int, int);
+void nfscl_uuidcheck(char *);
 void nfscl_fillclid(u_int64_t, char *, u_int8_t *, u_int16_t);
 void nfscl_filllockowner(void *, u_int8_t *, int);
 void nfscl_freeopen(struct nfsclopen *, int, bool);
diff --git a/sys/fs/nfsclient/nfs_clport.c b/sys/fs/nfsclient/nfs_clport.c
index cf163adc02d..d23051058ce 100644
--- a/sys/fs/nfsclient/nfs_clport.c
+++ b/sys/fs/nfsclient/nfs_clport.c
@@ -659,6 +659,37 @@ ncl_pager_setsize(struct vnode *vp, u_quad_t *nsizep)
 	return (setnsize);
 }
 
+/*
+ * If the uuid passed in is the DEFAULT_UUID, try and find an
+ * alternate to replace it with.
+ * If no alternate is available, set uuid to "" so that nfscl_fillclid()
+ * will use random bytes.
+ */
+void
+nfscl_uuidcheck(char *uuid)
+{
+	int ucplen, uuidlen;
+	char *ucp;
+
+	/*
+	 * If the uuid is the DEFAULT_UUID, try and get an alternative.
+	 */
+	uuidlen = strlen(uuid);
+	ucp = NULL;
+	if (uuidlen == strlen(DEFAULT_HOSTUUID) &&
+	    NFSBCMP(uuid, DEFAULT_HOSTUUID, uuidlen) == 0) {
+		*uuid = '\0';
+		/* Use smbios.system.uuid if it exists. */
+		if ((ucp = kern_getenv("smbios.system.uuid")) != NULL) {
+			ucplen = strlen(ucp);
+			if (ucplen < HOSTUUIDLEN && ucplen > 0)
+				strlcpy(uuid, ucp, HOSTUUIDLEN);
+		}
+	}
+	if (ucp != NULL)
+		freeenv(ucp);
+}
+
 /*
  * Fill in the client id name. For these bytes:
  * 1 - they must be unique
diff --git a/sys/fs/nfsclient/nfs_clrpcops.c b/sys/fs/nfsclient/nfs_clrpcops.c
index 974d08611a0..130cc499015 100644
--- a/sys/fs/nfsclient/nfs_clrpcops.c
+++ b/sys/fs/nfsclient/nfs_clrpcops.c
@@ -67,6 +67,7 @@ SYSCTL_U64(_vfs_nfs, OID_AUTO, maxcopyrange, CTLFLAG_RW,
 /*
  * Global variables
  */
+uint32_t nfs_exchangeboot = 0;
 extern struct nfsstatsv1 nfsstatsv1;
 extern int nfs_numnfscbd;
 extern struct timeval nfsboottime;
@@ -5537,7 +5538,7 @@ nfsrpc_exchangeid(struct nfsmount *nmp, struct nfsclclient *clp,
 	nfscl_reqstart(nd, NFSPROC_EXCHANGEID, nmp, NULL, 0, NULL, NULL,
 	    NFS_VER4, minorvers, NULL);
 	NFSM_BUILD(tl, uint32_t *, 2 * NFSX_UNSIGNED);
-	*tl++ = txdr_unsigned(nfsboottime.tv_sec);	/* Client owner */
+	*tl++ = txdr_unsigned(nfs_exchangeboot);	/* Client owner */
 	*tl = txdr_unsigned(clp->nfsc_rev);
 	(void) nfsm_strtom(nd, clp->nfsc_id, clp->nfsc_idlen);
 
diff --git a/sys/fs/nfsclient/nfs_clstate.c b/sys/fs/nfsclient/nfs_clstate.c
index 6dc97142b77..a511c31d520 100644
--- a/sys/fs/nfsclient/nfs_clstate.c
+++ b/sys/fs/nfsclient/nfs_clstate.c
@@ -89,6 +89,8 @@ extern u_int32_t newnfs_false, newnfs_true;
 extern int nfscl_debuglevel;
 extern int nfscl_enablecallb;
 extern int nfs_numnfscbd;
+extern struct timeval nfsboottime;
+extern uint32_t nfs_exchangeboot;
 NFSREQSPINLOCK;
 NFSCLSTATEMUTEX;
 int nfscl_inited = 0;
@@ -883,9 +885,11 @@ nfscl_getcl(struct mount *mp, struct ucred *cred, NFSPROC_T *p,
 	if (cred != NULL) {
 		getcredhostuuid(cred, uuid, sizeof uuid);
 		idlen = strlen(uuid);
-		if (idlen > 0)
+		if (idlen > 0) {
+			nfscl_uuidcheck(uuid);
+			idlen = strlen(uuid);
 			idlen += sizeof (u_int64_t);
-		else
+		} else
 			idlen += sizeof (u_int64_t) + 16; /* 16 random bytes */
 		newclp = malloc(
 		    sizeof (struct nfsclclient) + idlen - 1, M_NFSCLCLIENT,
@@ -996,6 +1000,15 @@ nfscl_getcl(struct mount *mp, struct ucred *cred, NFSPROC_T *p,
 		 * such that the server throws away the clientid before
 		 * receiving the SetClientIDConfirm.
 		 */
+		/*
+		 * Must be done here while locked and before calling
+		 * nfsrpc_setclient().
+		 */
+		if (nfs_exchangeboot == 0) {
+			nfs_exchangeboot = nfsboottime.tv_sec;
+			if (nfs_exchangeboot == 0)
+				nfs_exchangeboot = arc4random();
+		}
 		if (clp->nfsc_renew > 0)
 			clidinusedelay = NFSCL_LEASE(clp->nfsc_renew) * 2;
 		else
diff --git a/sys/fs/nfsclient/nfs_clvfsops.c b/sys/fs/nfsclient/nfs_clvfsops.c
index 212c88f2893..74e5e2dc9b1 100644
--- a/sys/fs/nfsclient/nfs_clvfsops.c
+++ b/sys/fs/nfsclient/nfs_clvfsops.c
@@ -567,7 +567,7 @@ nfs_mountdiskless(char *path,
     struct vnode **vpp, struct mount *mp)
 {
 	struct sockaddr *nam;
-	int dirlen, error;
+	int dirlen, error, minvers;
 	char *dirpath;
 
 	/*
@@ -580,9 +580,12 @@ nfs_mountdiskless(char *path,
 	else
 		dirlen = 0;
 	nam = sodupsockaddr((struct sockaddr *)sin, M_WAITOK);
+	minvers = 0;
+	if ((args->flags & NFSMNT_NFSV4) != 0)
+		minvers = -1;
 	if ((error = mountnfs(args, mp, nam, path, NULL, 0, dirpath, dirlen,
 	    NULL, 0, vpp, td->td_ucred, td, NFS_DEFAULT_NAMETIMEO, 
-	    NFS_DEFAULT_NEGNAMETIMEO, 0, 0, NULL, 0)) != 0) {
+	    NFS_DEFAULT_NEGNAMETIMEO, minvers, 0, NULL, 0)) != 0) {
 		printf("nfs_mountroot: mount %s on /: %d\n", path, error);
 		return (error);
 	}
diff --git a/sys/nfs/nfs_diskless.c b/sys/nfs/nfs_diskless.c
index 0f0cf80feee..d5278612d8d 100644
--- a/sys/nfs/nfs_diskless.c
+++ b/sys/nfs/nfs_diskless.c
@@ -119,6 +119,10 @@ nfs_parse_options(const char *envopts, struct nfs_args *nd)
 		else if (strcmp(o, "nfsv3") == 0) {
 			nd->flags &= ~NFSMNT_NFSV4;
 			nd->flags |= NFSMNT_NFSV3;
+		} else if (strcmp(o, "nfsv4") == 0) {
+			nd->flags &= ~NFSMNT_NFSV3;
+			nd->flags |= NFSMNT_NFSV4;
+			nd->sotype = SOCK_STREAM;
 		} else if (strcmp(o, "tcp") == 0)
 			nd->sotype = SOCK_STREAM;
 		else if (strcmp(o, "udp") == 0)
@@ -271,24 +275,33 @@ nfs_setup_diskless(void)
 			return;
 		}
 		nd3->root_saddr.sin_port = htons(NFS_PORT);
-		fhlen = decode_nfshandle("boot.nfsroot.nfshandle",
-		    &nd3->root_fh[0], NFSX_V3FHMAX);
-		if (fhlen == 0) {
-			printf("nfs_diskless: no NFS handle\n");
-			return;
+		if ((cp = kern_getenv("boot.nfsroot.options")) != NULL) {
+			nfs_parse_options(cp, &nd3->root_args);
+			freeenv(cp);
 		}
-		if (fhlen != nd3->root_fhsize) {
-			printf("nfs_diskless: bad NFS handle len=%d\n", fhlen);
-			return;
+		if ((nd3->root_args.flags & NFSMNT_NFSV4) == 0) {
+			fhlen = decode_nfshandle("boot.nfsroot.nfshandle",
+			    &nd3->root_fh[0], NFSX_V3FHMAX);
+			if (fhlen == 0) {
+				printf("nfs_diskless: no NFS handle\n");
+				return;
+			}
+			if (fhlen != nd3->root_fhsize) {
+				printf("nfs_diskless: bad NFS handle len=%d\n",
+				    fhlen);
+				return;
+			}
+		} else {
+			/*
+			 * For NFSv4, the file handle is derived from the
+			 * boot.nfsroot.path during mounting by NFSv4.
+			 */
+			nd3->root_fhsize = 0;
 		}
 		if ((cp = kern_getenv("boot.nfsroot.path")) != NULL) {
 			strncpy(nd3->root_hostnam, cp, MNAMELEN - 1);
 			freeenv(cp);
 		}
-		if ((cp = kern_getenv("boot.nfsroot.options")) != NULL) {
-			nfs_parse_options(cp, &nd3->root_args);
-			freeenv(cp);
-		}
 
 		nfs_diskless_valid = 3;
 	} else {