diff --git a/ChangeLog b/ChangeLog
index 0340cb72de..79863e30e8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Thu Mar 18 18:50:06 2004  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* mkconfig.rb: no longer embed srcdir and compile_dir into
+	  rbconfig.rb.
+
+	* ext/extmk.rb, lib/mkmf.rb: obtain top_srcdir and topdir from library
+	  paths.
+
 Thu Mar 18 17:46:35 2004  Masatoshi SEKI  <m_seki@mva.biglobe.ne.jp>
 
 	* lib/drb/drb.rb: do not undef :to_a.
diff --git a/ext/extmk.rb b/ext/extmk.rb
index 3e530e7316..427313bd58 100644
--- a/ext/extmk.rb
+++ b/ext/extmk.rb
@@ -20,22 +20,29 @@ $extlist = []
 $:.replace ["."]
 require 'rbconfig'
 
-srcdir = Config::CONFIG["srcdir"]
+srcdir = File.dirname(File.dirname(__FILE__))
 
 $:.replace [srcdir, srcdir+"/lib", "."]
 
+$topdir = "."
+$top_srcdir = srcdir
+
 require 'mkmf'
 require 'optparse/shellwords'
 
-$topdir = "."
-$top_srcdir = srcdir
-$hdrdir = $top_srcdir
-
 def sysquote(x)
   @quote ||= /human|os2|macos/ =~ (CROSS_COMPILING || RUBY_PLATFORM)
   @quote ? x.quote : x
 end
 
+def relative_from(path, base)
+  if File.expand_path(path) == File.expand_path(path, base)
+    path
+  else
+    File.join(base, path)
+  end
+end
+
 def extmake(target)
   print "#{$message} #{target}\n"
   $stdout.flush
@@ -59,9 +66,7 @@ def extmake(target)
     top_srcdir = $top_srcdir
     topdir = $topdir
     prefix = "../" * (target.count("/")+1)
-    if File.expand_path(top_srcdir) != File.expand_path(top_srcdir, dir)
-      $hdrdir = $top_srcdir = prefix + top_srcdir
-    end
+    $hdrdir = $top_srcdir = relative_from(top_srcdir, prefix)
     $topdir = prefix + $topdir
     $target = target
     $mdir = target
@@ -239,7 +244,7 @@ elsif $nmake
 else
   $ruby = '$(topdir)/miniruby' + EXEEXT
 end
-$ruby << " -I$(topdir) -I$(hdrdir)/lib"
+$ruby << " -I'$(topdir)' -I'$(hdrdir)/lib'"
 $config_h = '$(topdir)/config.h'
 
 MTIMES = [__FILE__, 'rbconfig.rb', srcdir+'/lib/mkmf.rb'].collect {|f| File.mtime(f)}
@@ -289,7 +294,7 @@ exts |= Dir.glob("#{ext_prefix}/*/**/MANIFEST").collect {|d|
 } unless $extension
 
 if $extout
-  Config.expand(extout = $extout+"/.")
+  Config.expand(extout = $extout+"/.", Config::CONFIG.merge("topdir"=>$topdir))
   if $install
     Config.expand(dest = "#{$destdir}#{$rubylibdir}")
     FileUtils.cp_r(extout, dest, :verbose => true, :noop => $dryrun)
@@ -304,10 +309,7 @@ dir = Dir.pwd
 FileUtils::makedirs('ext')
 Dir::chdir('ext')
 
-if File.expand_path(srcdir) != File.expand_path(srcdir, dir)
-  $hdrdir = $top_srcdir = "../" + srcdir
-end
-$topdir = ".."
+$hdrdir = $top_srcdir = relative_from(srcdir, $topdir = "..")
 exts.each do |d|
   extmake(d) or abort
 end
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index 39da5dfeb4..7561edaad9 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -38,7 +38,6 @@ unless defined? $configure_args
   end
 end
 
-$srcdir = CONFIG["srcdir"]
 $libdir = CONFIG["libdir"]
 $rubylibdir = CONFIG["rubylibdir"]
 $archdir = CONFIG["archdir"]
@@ -77,12 +76,13 @@ def map_dir(dir, map = nil)
   map.inject(dir) {|dir, (orig, new)| dir.gsub(orig, new)}
 end
 
-if not $extmk and File.exist?(Config::CONFIG["archdir"] + "/ruby.h")
+libdir = File.dirname(__FILE__)
+if libdir == Config::CONFIG["rubylibdir"] and
+    File.exist?(Config::CONFIG["archdir"] + "/ruby.h")
   $topdir = $hdrdir = $archdir
-elsif File.exist?($srcdir + "/ruby.h") and
-    File.exist?((compile_dir = Config::CONFIG['compile_dir']) + "/config.h")
-  $hdrdir = $srcdir
-  $topdir = compile_dir
+elsif File.exist?(($top_srcdir ||= File.dirname(libdir))  + "/ruby.h") and
+    File.exist?(($topdir ||= Config::CONFIG["topdir"]) + "/config.h")
+  $hdrdir = $top_srcdir
 else
   abort "can't find header files for ruby."
 end
@@ -728,7 +728,7 @@ end
 def configuration(srcdir)
   mk = []
   vpath = %w[$(srcdir) $(topdir) $(hdrdir)]
-  if $mingw && CONFIG['build_os'] == 'cygwin'
+  if !CROSS_COMPILING && CONFIG['build_os'] == 'cygwin' && CONFIG['target_os'] != 'cygwin'
     vpath.each {|p| p.sub!(/.*/, '$(shell cygpath -u \&)')}
   end
   mk << %{
@@ -739,7 +739,7 @@ SHELL = /bin/sh
 srcdir = #{srcdir}
 topdir = #{$topdir}
 hdrdir = #{$hdrdir}
-VPATH = #{vpath.join(File::PATH_SEPARATOR)}
+VPATH = #{vpath.join(CONFIG['PATH_SEPARATOR'])}
 }
   drive = File::PATH_SEPARATOR == ';' ? /\A\w:/ : /\A/
   if destdir = CONFIG["prefix"].scan(drive)[0] and !destdir.empty?
diff --git a/mkconfig.rb b/mkconfig.rb
index ef54287db5..08f8dc166e 100644
--- a/mkconfig.rb
+++ b/mkconfig.rb
@@ -1,7 +1,6 @@
 #!./miniruby -s
 
 # avoid warnings with -d.
-$srcdir ||= nil
 $install_name ||= nil
 $so_name ||= nil
 
@@ -9,7 +8,6 @@ require File.dirname($0)+"/lib/fileutils"
 mkconfig = File.basename($0)
 
 rbconfig_rb = ARGV[0] || 'rbconfig.rb'
-srcdir = $srcdir || '.'
 unless File.directory?(dir = File.dirname(rbconfig_rb))
   FileUtils.makedirs(dir, :verbose => true)
 end
@@ -54,17 +52,12 @@ File.foreach "config.status" do |line|
       v_others << v
     end
     has_version = true if name == "MAJOR"
-  elsif /^(?:ac_given_)?srcdir=(.*)/ =~ line
-    srcdir = $1.strip
   elsif /^ac_given_INSTALL=(.*)/ =~ line
     v_fast << "  CONFIG[\"INSTALL\"] = " + $1 + "\n"
   end
 #  break if /^CEOF/
 end
 
-srcdir = File.expand_path(srcdir)
-v_fast.unshift("  CONFIG[\"srcdir\"] = \"" + srcdir + "\"\n")
-
 v_fast.collect! do |x|
   if /"prefix"/ === x
     x.sub(/= (.*)/, '= (TOPDIR || DESTDIR + \1)')
@@ -113,7 +106,7 @@ print <<EOS
   CONFIG["archdir"] = "$(rubylibdir)/$(arch)"
   CONFIG["sitelibdir"] = "$(sitedir)/$(ruby_version)"
   CONFIG["sitearchdir"] = "$(sitelibdir)/$(sitearch)"
-  CONFIG["compile_dir"] = "#{Dir.pwd}"
+  CONFIG["topdir"] = File.dirname(__FILE__)
   MAKEFILE_CONFIG = {}
   CONFIG.each{|k,v| MAKEFILE_CONFIG[k] = v.dup}
   def Config::expand(val, config = CONFIG)