Index: stand/common/interp_lua.c
===================================================================
--- stand/common/interp_lua.c
+++ stand/common/interp_lua.c
@@ -43,6 +43,7 @@
 #include <lerrno.h>
 #include <lfs.h>
 #include <lutils.h>
+#include <lstd.h>
 
 struct interp_lua_softc {
 	lua_State	*luap;
@@ -124,10 +125,26 @@
 
 	filename = LOADER_LUA;
 	if (interp_include(filename) != 0) {
-                const char *errstr = lua_tostring(luap, -1);
-                errstr = errstr == NULL ? "unknown" : errstr;
-                printf("Startup error in %s:\nLUA ERROR: %s.\n", filename, errstr);
-                lua_pop(luap, 1);
+		if (lua_isnumber(luap, -1)) {
+			lua_Number exit_code;
+
+			exit_code = lua_tonumber(luap, -1);
+			lua_pop(luap, 1);
+
+			/*
+			 * INTERP_ERROR_EXIT is a fake error that indicates that
+			 * should just return and continue the loader sequence.
+			 */
+			if (exit_code != INTERP_ERROR_EXIT)
+				printf("Startup error in %s, exit code %jd.\n",
+				    filename, (intmax_t)exit_code);
+		} else {
+			const char *errstr = lua_tostring(luap, -1);
+			errstr = errstr == NULL ? "unknown" : errstr;
+			printf("Startup error in %s:\nLUA ERROR: %s.\n",
+			    filename, errstr);
+			lua_pop(luap, 1);
+		}
 	}
 }
 
Index: stand/liblua/lstd.h
===================================================================
--- stand/liblua/lstd.h
+++ stand/liblua/lstd.h
@@ -80,4 +80,17 @@
 #define fflush	/* */
 #define fgets(b, l, s) fgetstr((b), (l), 0)
 
+/*
+ * We get one object to represent an error when returning from within the lua
+ * pcall context.  To avoid colliding with perhaps other legitimate error
+ * circumstances, we derive the below magic number and use that as our basis for
+ * errors.  This 'b', 's', 'd' magic should hopefully be unique enough that we
+ * can determine that this is the kind of error we think it is.  Also note that
+ * Lua itself uses strings for its error objects, so we're likely pretty safe
+ * anyways.
+ */
+#define	INTERP_ERROR_MAGIC	(0x62736400)
+#define	INTERP_ERROR(n)		(INTERP_ERROR_MAGIC + (n))
+#define	INTERP_ERROR_EXIT	INTERP_ERROR(0)
+
 #endif /* LSTD_H */
Index: stand/liblua/lutils.c
===================================================================
--- stand/liblua/lutils.c
+++ stand/liblua/lutils.c
@@ -36,6 +36,29 @@
 #include "lutils.h"
 #include "bootstrap.h"
 
+/*
+ * Exits the interpreter cleanly, proceeding to autoboot or loader prompt
+ * depending on configuration.
+ */
+static int
+lua_exit(lua_State *L)
+{
+
+	/*
+	 * Be strict about parameters for now, in case we want to change usage
+	 * down the road.
+	 */
+	if (lua_gettop(L) != 0)
+		lua_pushliteral(L,
+		    "loader.exit() must not be called with arguments.");
+	else
+		lua_pushnumber(L, INTERP_ERROR_EXIT);
+
+	lua_error(L);
+	/* NORETURN */
+	return (1);
+}
+
 /*
  * Like loader.perform, except args are passed already parsed
  * on the stack.
@@ -351,6 +374,7 @@
 	REG_SIMPLE(delay),
 	REG_SIMPLE(command_error),
 	REG_SIMPLE(command),
+	REG_SIMPLE(exit),
 	REG_SIMPLE(interpret),
 	REG_SIMPLE(parse),
 	REG_SIMPLE(getenv),