Index: configure.in
===================================================================
--- configure.in	(revision 35862)
+++ configure.in	(working copy)
@@ -3012,6 +3012,13 @@ until VENDOR_DIR=`eval echo \\"${dir}\\"
     dir="${VENDOR_DIR}"
 done
 
+AC_ARG_WITH(rubygemsdir,
+           AS_HELP_STRING([--with-rubygemsdir=DIR], [custom rubygems directory]),
+            [rubygemsdir=$withval])
+if test "$rubygemsdir" != ""; then
+    AC_DEFINE_UNQUOTED(RUBYGEMS_DIR,"$rubygemsdir")
+fi
+
 if test "${LOAD_RELATIVE+set}"; then
     AC_DEFINE_UNQUOTED(LOAD_RELATIVE, $LOAD_RELATIVE)
     RUBY_EXEC_PREFIX=""
@@ -3072,6 +3079,7 @@ AC_SUBST(sitearch)dnl
 AC_SUBST(ruby_version)dnl
 AC_SUBST(sitedir)dnl
 AC_SUBST(vendordir)dnl
+AC_SUBST(rubygemsdir)dnl
 
 configure_args=$ac_configure_args
 AC_SUBST(configure_args)dnl
Index: version.c
===================================================================
--- version.c	(revision 35862)
+++ version.c	(working copy)
@@ -88,6 +88,10 @@ const char ruby_initial_load_paths[] =
     RUBY_VENDOR_LIB "\0"
 #endif
 
+#ifdef RUBYGEMS_DIR
+    RUBYGEMS_DIR "\0"
+#endif
+
     RUBY_LIB "\0"
 #ifdef RUBY_THIN_ARCHLIB
     RUBY_THIN_ARCHLIB "\0"
Index: tool/rbinstall.rb
===================================================================
--- tool/rbinstall.rb	(revision 35862)
+++ tool/rbinstall.rb	(working copy)
@@ -311,6 +311,7 @@ sitelibdir = CONFIG["sitelibdir"]
 sitearchlibdir = CONFIG["sitearchdir"]
 vendorlibdir = CONFIG["vendorlibdir"]
 vendorarchlibdir = CONFIG["vendorarchdir"]
+rubygemsdir = CONFIG["rubygemsdir"]
 mandir = CONFIG["mandir", true]
 docdir = CONFIG["docdir", true]
 configure_args = Shellwords.shellwords(CONFIG["configure_args"])
@@ -498,7 +499,15 @@ end
 install?(:local, :comm, :lib) do
   prepare "library scripts", rubylibdir
   noinst = %w[README* *.txt *.rdoc]
+  noinst += %w[*ubygems.rb rubygems/ datadir.rb] if rubygemsdir
   install_recursive(File.join(srcdir, "lib"), rubylibdir, :no_install => noinst, :mode => $data_mode)
+  if rubygemsdir
+    noinst = %w[obsolete.rb]
+    install_recursive(File.join(srcdir, "lib", "rubygems"), File.join(rubygemsdir, "rubygems"), :mode => $data_mode)
+    install_recursive(File.join(srcdir, "lib", "rbconfig"), File.join(rubygemsdir, "rbconfig"), :no_install => noinst, :mode => $data_mode)
+    install(File.join(srcdir, "lib", "ubygems.rb"), File.join(rubygemsdir, "ubygems.rb"), :mode => $data_mode)
+    install(File.join(srcdir, "lib", "rubygems.rb"), File.join(rubygemsdir, "rubygems.rb"), :mode => $data_mode)
+  end
 end
 
 install?(:local, :arch, :lib) do
Index: tool/mkconfig.rb
===================================================================
--- tool/mkconfig.rb	(revision 35862)
+++ tool/mkconfig.rb	(working copy)
@@ -77,6 +77,7 @@ File.foreach "config.status" do |line|
     when /^RUBY_SO_NAME$/; next if $so_name
     when /^arch$/; if val.empty? then val = arch else arch = val end
     when /^sitearch/; val = '$(arch)' if val.empty?
+    when /^rubygemsdir/; next if val.empty?
     end
     case val
     when /^\$\(ac_\w+\)$/; next