Index: usr.bin/config/defs.h
===================================================================
RCS file: /cvsroot/src/usr.bin/config/defs.h,v
retrieving revision 1.45
diff -p -u -r1.45 defs.h
--- usr.bin/config/defs.h	5 May 2014 19:08:13 -0000	1.45
+++ usr.bin/config/defs.h	17 Jul 2014 00:09:37 -0000
@@ -521,7 +521,8 @@ void	checkfiles(void);
 int	fixfiles(void);		/* finalize */
 int	fixobjects(void);
 int	fixdevsw(void);
-void	addfile(const char *, struct condexpr *, int, const char *);
+void	addfile(const char *, struct condexpr *, int, const char *,
+	    const char *);
 void	addobject(const char *, struct condexpr *, int);
 int	expr_eval(struct condexpr *, int (*)(const char *, void *), void *);
 
Index: usr.bin/config/files.c
===================================================================
RCS file: /cvsroot/src/usr.bin/config/files.c,v
retrieving revision 1.12
diff -p -u -r1.12 files.c
--- usr.bin/config/files.c	21 May 2014 05:25:34 -0000	1.12
+++ usr.bin/config/files.c	17 Jul 2014 00:09:37 -0000
@@ -82,7 +82,8 @@ initfiles(void)
 }
 
 void
-addfile(const char *path, struct condexpr *optx, int flags, const char *rule)
+addfile(const char *path, struct condexpr *optx, int flags,
+    const char *override_base, const char *rule)
 {
 	struct files *fi;
 	const char *dotp, *tail;
@@ -103,17 +104,29 @@ addfile(const char *path, struct condexp
 		goto bad;
 	}
 
-	/* find last part of pathname, and same without trailing suffix */
-	tail = strrchr(path, '/');
-	if (tail == NULL)
-		tail = path;
-	else
-		tail++;
-	dotp = strrchr(tail, '.');
-	if (dotp == NULL || dotp[1] == 0 ||
-	    (baselen = dotp - tail) >= sizeof(base)) {
-		cfgerror("invalid pathname `%s'", path);
-		goto bad;
+	if (override_base != NULL) {
+		tail = override_base;
+		baselen = strlen(override_base);
+		if (baselen >= sizeof(base)) {
+			cfgerror("invalid basename `%s'", override_base);
+			goto bad;
+		}
+	} else {
+		/*
+		 * find last part of pathname, and same without
+		 * trailing suffix
+		 */
+		tail = strrchr(path, '/');
+		if (tail == NULL)
+			tail = path;
+		else
+			tail++;
+		dotp = strrchr(tail, '.');
+		if (dotp == NULL || dotp[1] == 0 ||
+		    (baselen = dotp - tail) >= sizeof(base)) {
+			cfgerror("invalid pathname `%s'", path);
+			goto bad;
+		}
 	}
 
 	/*
Index: usr.bin/config/gram.y
===================================================================
RCS file: /cvsroot/src/usr.bin/config/gram.y,v
retrieving revision 1.39
diff -p -u -r1.39 gram.y
--- usr.bin/config/gram.y	29 May 2014 07:47:45 -0000	1.39
+++ usr.bin/config/gram.y	17 Jul 2014 00:09:37 -0000
@@ -162,7 +162,7 @@ static struct loclist *namelocvals(const
 }
 
 %token	AND AT ATTACH
-%token	BLOCK BUILD
+%token	BASE BLOCK BUILD
 %token	CHAR COLONEQ COMPILE_WITH CONFIG
 %token	DEFFS DEFINE DEFOPT DEFPARAM DEFFLAG DEFPSEUDO DEFPSEUDODEV
 %token	DEVICE DEVCLASS DUMPS DEVICE_MAJOR
@@ -188,7 +188,7 @@ static struct loclist *namelocvals(const
 %type	<condexpr>	 cond_base_expr
 %type	<str>	fs_spec
 %type	<val>	fflags fflag oflags oflag
-%type	<str>	rule
+%type	<str>	base rule
 %type	<attr>	depend
 %type	<devb>	devbase
 %type	<deva>	devattach_opt
@@ -342,9 +342,13 @@ definition:
 	| VERSION NUMBER		{ setversion($2.val); }
 ;
 
-/* source file: file foo/bar.c bar|baz needs-flag compile-with blah */
+/*
+ * source file:
+ *
+ *   file foo/bar.c bar|baz needs-flag base foo_bar compile-with blah
+ */
 file:
-	XFILE filename fopts fflags rule	{ addfile($2, $3, $4, $5); }
+	XFILE filename fopts fflags base rule	{ addfile($2, $3, $4, $5, $6); }
 ;
 
 /* file options: optional expression of conditions */
@@ -365,6 +369,11 @@ fflag:
 	| NEEDS_FLAG			{ $$ = FI_NEEDSFLAG; }
 ;
 
+/* base name for object file */
+base:
+	  /* empty */			{ $$ = NULL; }
+	| BASE stringvalue		{ $$ = $2; }
+
 /* extra compile directive for a source file */
 rule:
 	  /* empty */			{ $$ = NULL; }
Index: usr.bin/config/scan.l
===================================================================
RCS file: /cvsroot/src/usr.bin/config/scan.l,v
retrieving revision 1.17
diff -p -u -r1.17 scan.l
--- usr.bin/config/scan.l	20 Mar 2012 20:34:57 -0000	1.17
+++ usr.bin/config/scan.l	17 Jul 2014 00:09:37 -0000
@@ -125,6 +125,7 @@ RESTOFLINE	[ \t]*(#[^\n]*)?\n
 and		return AND;
 at		return AT;
 attach		return ATTACH;
+base		return BASE;
 block		return BLOCK;
 build		return BUILD;
 char		return CHAR;