diff --git a/config/module2dir.pl b/config/module2dir.pl
new file mode 100755
index 000000000000..4c1d61a1c5d2
--- /dev/null
+++ b/config/module2dir.pl
@@ -0,0 +1,151 @@
+#!/usr/bin/perl -w
+
+#
+# Create a mapping from symbolic component name to directory name(s).
+#
+# Tue Oct 16 16:48:36 PDT 2001
+# <mcafee@netscape.com>
+
+sub PrintUsage {
+  die <<END_USAGE
+  Prints out directories needed for a given list of components.
+  usage: module2dir.pl [--list-only] <component-name1> <component-name2> ...
+END_USAGE
+}
+
+my %map = (
+  'accessibility',      'accessible',
+  'addrbook',           'mailnews/addrbook',
+  'appcomps',           'xpfe/components',
+  'appshell',           'xpfe/appshell',
+  'appstartup',         'embedding/components/appstartup',
+  'browser',            'xpfe/browser',
+  'caps',               'caps',
+  'chardet',            'intl/chardet',
+  'chrome',             'rdf/chrome',
+  'content',            'content',
+  'content_xsl',        'content/xsl/document',
+  'cookie',             'extensions/cookie',
+  'dbm',                'dbm',
+  'docshell',           'docshell',
+  'dom',                'dom',
+  'editor',             'editor',
+  'embed_base',         'embedding/base',
+  'embedcomponents',    'embedding/components/appstartup',
+  'expat',              'expat',
+  'exthandler',         'uriloader/exthandler',
+  'find',               'xpfe/componets/find',
+  'gfx',                'gfx',
+  'gfx2',               'gfx2',
+  'gtkxtbin',           'widget/src/gtkxtbin',
+  'helperAppDlg',       'embedding/components/ui/helperAppDlg',
+  'htmlparser',         'htmlparser',
+  'imglib2',            'modules/libpr0n',
+  'import',             'mailnews/import',
+  'intl',               'intl',
+  'jar',                'modules/libjar',
+  'java',               'sun-java/stubs',
+  'jprof',              'tools/jprof',
+  'js',                 'js',
+  'jsconsole',          'embedding/components/jsconsole',
+  'layout',             'layout',
+  'libreg',             'modules/libreg',
+  'locale',             'intl/locale',
+  'lwbrk',              'intl/lwbrk',
+  'mailnews',           'mailnews',
+  'mime',               'mailnews/mime',
+  'mimetype',           'netwerk/mime',
+  'mork',               'mailnews/db/mork',
+  'mozcomps',           'xpfe/components',
+  'mozldap',            'directory/xpcom/base',
+  'mpfilelocprovider',  'modules/mpfilelocprovider',
+  'msgbase',            'mailnews/base',
+  'msgbaseutil',        'mailnews/base/util',
+  'msgcompose',         'mailnews/compose',
+  'msgdb',              'mailnews/db/msgdb',
+  'msgimap',            'mailnews/imap',
+  'msglocal',           'mailnews/local',
+  'msgnews',            'mailnews/news',
+  'necko',              'netwerk',
+  'necko2',             'netwerk/protocol',
+  'nkcache',            'netwerk/cache',
+  'oji',                'modules/oji',
+  'plugin',             'modules/plugin',
+  'pref',               'modules/libpref',
+  'prefmigr',           'profile/pref-migrator',
+  'profile',            'profile',
+  'rdf',                'rdf',
+  'rdfutil',            'rdf/util',
+  'shistory',           'xpfe/components/shistory',
+  'sidebar',            'xpfe/components/sidebar',
+  'string',             'string',
+  'timer',              'widget/timer',
+  'transformiix',       'extensions/transformiix',
+  'txmgr',              'editor/txmgr',
+  'txtsvc',             'editor/txtsvc',
+  'uconv',              'intl/uconv',
+  'unicharutil',        'intl/unicharutil',
+  'uriloader',          'uriloader',
+  'util',               'modules/libutil',
+  'view',               'view',
+  'wallet',             'extensions/wallet',
+  'webbrwsr',           'embedding/browser/webBrowser',
+  'webshell',           'webshell',
+  'widget',             'widget',
+  'windowwatcher',      'embedding/components/windowwatcher',
+  'xlibrgb',            'gfx/src/xlibrgb',
+  'xmlextras',          'extensions/xmlextras',
+  'xpcom',              'xpcom',
+  'xpconnect',          'js/src/xpconnect',
+  'xpconnect_tests',    'js/src/xpconnect/tests',
+  'xpinstall',          'xpinstall',
+  'xremoteservice',     'xpfe/components/xremote',
+  'xul',                'content/xul/content',
+  'xuldoc',             'content/xul/document',
+  'xultmpl',            'content/xul/templates',
+);
+
+
+sub dir_for_required_component {
+  my ($component) = @_;
+  my $rv;
+  my $dir;
+
+  $dir = $map{$component};
+  if($dir) {
+	$rv = "mozilla/$dir";
+  } else {
+	$rv = 0;
+  }
+  return $rv;
+}
+
+my $list_only_mode = 0;
+{
+  PrintUsage() if $#ARGV == -1;
+
+  # Test for --list-only argument, and shift args if found.
+  # Hack, should use Getopt::Long for proper arg processing.
+  if($ARGV[0] eq "--list-only") {
+	$list_only_mode = 1;
+	shift @ARGV;
+  }
+
+  my $arg;
+  my $dir;
+  while ($arg = shift @ARGV) {
+	$dir = dir_for_required_component($arg);
+	if($dir) {
+      if($list_only_mode) {
+		print $dir, " ";
+	  } else {
+		print "$arg: ", $dir, "\n";
+	  }
+	} else {
+	  # do nothing
+	}
+  }
+  if($dir && $list_only_mode) {
+	print "\n";
+  }
+}