Index: lib/libc/sys/send.2
===================================================================
--- lib/libc/sys/send.2
+++ lib/libc/sys/send.2
@@ -122,6 +122,7 @@
 #define	MSG_OOB		0x00001 /* process out-of-band data */
 #define	MSG_DONTROUTE	0x00004 /* bypass routing, use direct interface */
 #define MSG_EOR		0x00008 /* data completes record */
+#define	MSG_DONTWAIT	0x00080	/* this message should be nonblocking */
 #define	MSG_EOF		0x00100 /* data completes transaction */
 #define	MSG_NOSIGNAL	0x20000 /* do not generate SIGPIPE on EOF */
 .Ed
Index: sys/kern/uipc_socket.c
===================================================================
--- sys/kern/uipc_socket.c
+++ sys/kern/uipc_socket.c
@@ -1522,7 +1522,8 @@
 		}
 		if (space < resid + clen &&
 		    (atomic || space < so->so_snd.sb_lowat || space < clen)) {
-			if ((so->so_state & SS_NBIO) || (flags & MSG_NBIO)) {
+			if ((so->so_state & SS_NBIO) ||
+			    (flags & (MSG_NBIO | MSG_DONTWAIT)) != 0) {
 				SOCKBUF_UNLOCK(&so->so_snd);
 				error = EWOULDBLOCK;
 				goto release;
Index: sys/netinet/sctp_output.c
===================================================================
--- sys/netinet/sctp_output.c
+++ sys/netinet/sctp_output.c
@@ -12836,7 +12836,7 @@
 		}
 	}
 	if (SCTP_SO_IS_NBIO(so)
-	    || (flags & MSG_NBIO)
+	    || (flags & (MSG_NBIO | MSG_DONTWAIT)) != 0
 	    ) {
 		non_blocking = 1;
 	}
Index: sys/ofed/drivers/infiniband/ulp/sdp/sdp_main.c
===================================================================
--- sys/ofed/drivers/infiniband/ulp/sdp/sdp_main.c
+++ sys/ofed/drivers/infiniband/ulp/sdp/sdp_main.c
@@ -1124,7 +1124,8 @@
 		}
 		if (space < resid &&
 		    (atomic || space < so->so_snd.sb_lowat)) {
-			if ((so->so_state & SS_NBIO) || (flags & MSG_NBIO)) {
+			if ((so->so_state & SS_NBIO) ||
+			    (flags & (MSG_NBIO | MSG_DONTWAIT)) != 0) {
 				SOCKBUF_UNLOCK(&so->so_snd);
 				error = EWOULDBLOCK;
 				goto release;