diff --git a/lib-src/Makefile.in b/lib-src/Makefile.in
index 15ba317c928..eda56a40e9a 100644
--- a/lib-src/Makefile.in
+++ b/lib-src/Makefile.in
@@ -58,6 +58,16 @@ srcdir=.
 # be installed at once.
 archlibdir=${libdir}/emacs/${version}/${configname}
 
+# ====================== Developer's configuration =======================
+
+# The following assignments make sense if you're running Emacs on a single
+# machine, one version at a time, and  you want changes to the lisp and etc
+# directories in the source tree to show up immediately in your working
+# environment.  It saves a great deal of disk space by not duplicating the
+# lisp and etc directories.
+#
+# archlibdir=${srcdir}/bin
+
 # ==================== Utility Programs for the Build ====================
 
 # Allow the user to specify the install program.
@@ -82,6 +92,9 @@ SCRIPTS= rcs2log vcdiff
 
 EXECUTABLES= ${UTILITIES} ${INSTALLABLES} ${SCRIPTS}
 
+SOURCES = COPYING ChangeLog Makefile.in README aixcc.lex emacs.csh \
+	makedoc.com *.[chy] rcs2log vcdiff
+
 ### We need to #define emacs to get the right versions of some files.
 ### Some other files - those shared with other GNU utilities - need
 ### HAVE_CONFIG_H #defined before they know they can take advantage of
@@ -140,6 +153,12 @@ realclean: distclean
 extraclean: realclean
 	-rm -f *~ \#*
 
+unlock:
+	chmod u+w $(SOURCES)
+
+relock:
+	chmod u-w $(SOURCES)
+
 # Test the contents of the directory.
 check:
 	@echo "We don't have any tests for GNU Emacs yet."