Index: usr.sbin/syslogd/syslogd.8
===================================================================
--- usr.sbin/syslogd/syslogd.8
+++ usr.sbin/syslogd/syslogd.8
@@ -28,7 +28,7 @@
 .\"     @(#)syslogd.8	8.1 (Berkeley) 6/6/93
 .\" $FreeBSD$
 .\"
-.Dd June 16, 2015
+.Dd January 22, 2016
 .Dt SYSLOGD 8
 .Os
 .Sh NAME
@@ -36,7 +36,7 @@
 .Nd log systems messages
 .Sh SYNOPSIS
 .Nm
-.Op Fl 468ACcdFkNnosTuv
+.Op Fl 468ACcdFkNnoOsTuv
 .Op Fl a Ar allowed_peer
 .Op Fl b Ar bind_address
 .Op Fl f Ar config_file
@@ -254,6 +254,10 @@
 .Xr getbootfile 3 .
 Without this, the kernel message prefix is always
 .Dq Li kernel: .
+.It Fl O 
+Disable the protection of
+.Nm
+from being killed if the system exhausts available memory and swap.
 .It Fl p
 Specify the pathname of an alternate log socket to be used instead;
 the default is
@@ -353,6 +357,9 @@
 option is specified);
 therefore, they must be created manually before running
 .Nm .
+Also by default
+.Nm
+is protected against OOM.
 .Pp
 The date and time are taken from the received message.
 If the format of the timestamp field is incorrect,
Index: usr.sbin/syslogd/syslogd.c
===================================================================
--- usr.sbin/syslogd/syslogd.c
+++ usr.sbin/syslogd/syslogd.c
@@ -89,6 +89,7 @@
 #include <sys/resource.h>
 #include <sys/syslimits.h>
 #include <sys/types.h>
+#include <sys/procctl.h>
 
 #include <netinet/in.h>
 #include <netdb.h>
@@ -290,6 +291,7 @@
 static int	MarkInterval = 20 * 60;	/* interval between marks in seconds */
 static int	MarkSeq;	/* mark sequence number */
 static int	NoBind;		/* don't bind() as suggested by RFC 3164 */
+static int	ProtectMode = 1;/* true by default to protect from OOM killer */
 static int	SecureMode;	/* when true, receive only unix domain socks */
 #ifdef INET6
 static int	family = PF_UNSPEC; /* protocol family (IPv4, IPv6 or both) */
@@ -384,7 +386,7 @@
 
 	STAILQ_INIT(&hqueue);
 
-	while ((ch = getopt(argc, argv, "468Aa:b:cCdf:Fkl:m:nNop:P:sS:Tuv"))
+	while ((ch = getopt(argc, argv, "468Aa:b:cCdf:Fkl:m:nNoOp:P:sS:Tuv"))
 	    != -1)
 		switch (ch) {
 		case '4':
@@ -481,6 +483,13 @@
 		case 'o':
 			use_bootfile = 1;
 			break;
+		case 'O':
+			/*
+			 * Protect itself from being killed
+			 * when swap space is exhausted.
+			 */
+			ProtectMode--;
+			break;
 		case 'p':		/* path */
 			if (strlen(optarg) >= sizeof(sunx.sun_path))
 				errx(1, "%s path too long, exiting", optarg);
@@ -630,6 +639,13 @@
 	/* tuck my process id away */
 	pidfile_write(pfh);
 
+    dprintf("==> ProtectMode: %d\n", ProtectMode);
+	if (ProtectMode) {
+        dprintf("==> ProtectMode: ON\n");
+		int p_flags = PPROT_SET;
+		procctl(P_PID, getpid(), PROC_SPROTECT, &p_flags);
+	}
+
 	dprintf("off & running....\n");
 
 	init(0);