Index: sys/kern/imgact_elf.c
===================================================================
--- sys/kern/imgact_elf.c
+++ sys/kern/imgact_elf.c
@@ -1822,6 +1822,8 @@
 static void
 __elfN(note_prpsinfo)(void *arg, struct sbuf *sb, size_t *sizep)
 {
+	size_t len;
+	char *cp, *end;
 	struct proc *p;
 	elf_prpsinfo_t *psinfo;
 
@@ -1832,12 +1834,24 @@
 		psinfo->pr_version = PRPSINFO_VERSION;
 		psinfo->pr_psinfosz = sizeof(elf_prpsinfo_t);
 		strlcpy(psinfo->pr_fname, p->p_comm, sizeof(psinfo->pr_fname));
-		/*
-		 * XXX - We don't fill in the command line arguments properly
-		 * yet.
-		 */
-		strlcpy(psinfo->pr_psargs, p->p_comm,
-		    sizeof(psinfo->pr_psargs));
+		PROC_LOCK(p);
+		if (p->p_args != NULL) {
+			len = sizeof(psinfo->pr_psargs) - 1;
+			if (len > p->p_args->ar_length)
+				len = p->p_args->ar_length;
+			memcpy(psinfo->pr_psargs, p->p_args->ar_args, len);
+			cp = psinfo->pr_psargs;
+			end = cp + len - 1;
+			for (;;) {
+				cp = memchr(cp, '\0', end - cp);
+				if (cp == NULL)
+					break;
+				*cp = ' ';
+			}
+		} else
+			strlcpy(psinfo->pr_psargs, p->p_comm,
+			    sizeof(psinfo->pr_psargs));
+		PROC_UNLOCK(p);
 
 		sbuf_bcat(sb, psinfo, sizeof(*psinfo));
 		free(psinfo, M_TEMP);
Index: usr.bin/gcore/elfcore.c
===================================================================
--- usr.bin/gcore/elfcore.c
+++ usr.bin/gcore/elfcore.c
@@ -538,6 +538,7 @@
 static void *
 elf_note_prpsinfo(void *arg, size_t *sizep)
 {
+	char *cp, *end;
 	pid_t pid;
 	elfcore_prpsinfo_t *psinfo;
 	struct kinfo_proc kip;
@@ -561,7 +562,20 @@
 	if (kip.ki_pid != pid)
 		err(1, "kern.proc.pid.%u", pid);
 	strlcpy(psinfo->pr_fname, kip.ki_comm, sizeof(psinfo->pr_fname));
-	strlcpy(psinfo->pr_psargs, psinfo->pr_fname, sizeof(psinfo->pr_psargs));
+	name[2] = KERN_PROC_ARGS;
+	len = sizeof(psinfo->pr_psargs) - 1;
+	if (sysctl(name, 4, psinfo->pr_psargs, &len, NULL, 0) == 0 && len > 0) {
+		cp = psinfo->pr_psargs;
+		end = cp + len - 1;
+		for (;;) {
+			cp = memchr(cp, '\0', end - cp);
+			if (cp == NULL)
+				break;
+			*cp = ' ';
+		}
+	} else
+		strlcpy(psinfo->pr_psargs, kip.ki_comm,
+		    sizeof(psinfo->pr_psargs));
 
 	*sizep = sizeof(*psinfo);
 	return (psinfo);