diff --git a/stand/defaults/loader.conf b/stand/defaults/loader.conf
--- a/stand/defaults/loader.conf
+++ b/stand/defaults/loader.conf
@@ -163,6 +163,8 @@
 #kern.ipc.nsfbufs=""		# Set the number of sendfile(2) bufs
 #net.inet.tcp.tcbhashsize=""	# Set the value of TCBHASHSIZE
 #vfs.root.mountfrom=""		# Specify root partition
+#vfs.mountroot.onfail		# Action to take on failure to mountroot:
+				# "continue", "panic", "reboot", or "retry"
 #vfs.mountroot.onfallback="ask"	# Action to take if no root found:
 				# "ask" (mountroot prompt), "reboot"
 #vm.kmem_size=""		# Sets the size of kernel memory (bytes)
diff --git a/sys/kern/vfs_mountroot.c b/sys/kern/vfs_mountroot.c
--- a/sys/kern/vfs_mountroot.c
+++ b/sys/kern/vfs_mountroot.c
@@ -900,7 +900,13 @@
 	char *s, *tok, *mnt, *opt;
 	int error;
 
-	sbuf_printf(sb, ".onfail panic\n");
+	s = kern_getenv("vfs.mountroot.onfail");
+	if (s != NULL) {
+		sbuf_printf(sb, ".onfail %s\n", s);
+		freeenv(s);
+	} else {
+		sbuf_printf(sb, ".onfail panic\n");
+	}
 	sbuf_printf(sb, ".timeout %d\n", root_mount_timeout);
 	if (boothowto & RB_ASKNAME)
 		sbuf_printf(sb, ".ask\n");