diff --git a/ChangeLog b/ChangeLog
index 6a1d84fa..9e6cb210 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2007-11-09  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
 
+	New config files output variable `top_build_prefix'.
+	* lib/autoconf/status.m4 (_AC_OUTPUT_FILE): Substitute
+	`top_build_prefix'.
+	* doc/autoconf.texi (Preset Output Variables): Document it.
+	* NEWS: Update.
+	Report by Bob Friesenhahn.
+
 	Avoid expr for arithmetic evaluation if the shell accepts $((...)).
 	* lib/autotest/general.m4 (AT_INIT) <at_func_arith>: New
 	function, to parametrize arithmetic with expr vs. the shell.
diff --git a/NEWS b/NEWS
index 77cd6f50..854c54a1 100644
--- a/NEWS
+++ b/NEWS
@@ -13,6 +13,8 @@ GNU Autoconf NEWS - User visible changes.
      Further, for config headers, the total size of values is not limited by
      the POSIX length limit of text lines any more, only each single line.
 
+** New config variable `top_build_prefix'.
+
 ** Autoconf is now licensed under the General Public License version 3
    or later (GPLv3+).  As with earlier versions, the license includes
    an exception clause so that you may release a configure script
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 9025359d..421056e0 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -2436,6 +2436,16 @@ The relative name of the top level of the current build tree.  In the
 top-level directory, this is the same as @code{builddir}.
 @end defvar
 
+@defvar top_build_prefix
+@ovindex top_build_prefix
+The relative name of the top level of the current build tree with final
+slash if nonemtpy.  This is the same as @code{top_builddir}, except that
+it contains of zero of more runs of @code{../}, so it should not be
+appended with a slash for concatenation.  This helps for @command{make}
+implementations that otherwise do not treat @file{./file} and @file{file}
+as equal in the toplevel build directory.
+@end defvar
+
 @defvar abs_top_builddir
 @ovindex abs_top_builddir
 Absolute name of @code{top_builddir}.
diff --git a/lib/autoconf/status.m4 b/lib/autoconf/status.m4
index 350d370e..4412df0f 100644
--- a/lib/autoconf/status.m4
+++ b/lib/autoconf/status.m4
@@ -622,6 +622,7 @@ dnl configure_input is a somewhat special, so we don't call AC_SUBST_TRACE.
 s&@configure_input@&$configure_input&;t t
 dnl During the transition period, this is a special case:
 s&@top_builddir@&$ac_top_builddir_sub&;t t[]AC_SUBST_TRACE([top_builddir])
+s&@top_build_prefix@&$ac_top_build_prefix&;t t[]AC_SUBST_TRACE([top_build_prefix])
 m4_foreach([_AC_Var], [srcdir, abs_srcdir, top_srcdir, abs_top_srcdir,
 			builddir, abs_builddir,
 			abs_top_builddir]AC_PROVIDE_IFELSE([AC_PROG_INSTALL], [[, INSTALL]])AC_PROVIDE_IFELSE([AC_PROG_MKDIR_P], [[, MKDIR_P]]),