Index: pym/portage/dbapi/porttree.py
===================================================================
--- pym/portage/dbapi/porttree.py	(revision 13324)
+++ pym/portage/dbapi/porttree.py	(revision 13325)
@@ -173,10 +173,15 @@
 
 		self._repo_info = {}
 		eclass_dbs = {porttree_root : self.eclassdb}
+		local_repo_configs = self.mysettings._local_repo_configs
+		default_loc_repo_config = None
+		if local_repo_configs is not None:
+			default_loc_repo_config = local_repo_configs.get('DEFAULT')
 		for path in self.porttrees:
 			if path in self._repo_info:
 				continue
 
+			repo_name = self._repository_map.get(path)
 			layout_filename = os.path.join(path, "metadata/layout.conf")
 			layout_file = KeyValuePairFileLoader(layout_filename, None, None)
 			layout_data, layout_errors = layout_file.load()
@@ -200,6 +205,24 @@
 
 			porttrees.append(path)
 
+			if local_repo_configs is not None:
+				loc_repo_conf = None
+				if repo_name is not None:
+					loc_repo_conf = local_repo_configs.get(repo_name)
+				if loc_repo_conf is None:
+					loc_repo_conf = default_loc_repo_config
+				if loc_repo_conf is not None:
+					for other_name in loc_repo_conf.eclass_overrides:
+						other_path = self.treemap.get(other_name)
+						if other_path is None:
+							writemsg_level(("Unavailable repository '%s' " + \
+								"referenced by eclass-overrides entry in " + \
+								"'%s'\n") % (other_name,
+								self.mysettings._local_repo_conf_path),
+								level=logging.ERROR, noiselevel=-1)
+							continue
+						porttrees.append(other_path)
+
 			eclass_db = None
 			for porttree in porttrees:
 				tree_db = eclass_dbs.get(porttree)
@@ -211,8 +234,7 @@
 				else:
 					eclass_db.append(tree_db)
 
-			self._repo_info[path] = _repo_info(self._repository_map.get(path),
-				path, eclass_db)
+			self._repo_info[path] = _repo_info(repo_name, path, eclass_db)
 
 		self.auxdbmodule = self.mysettings.load_best_module("portdbapi.auxdbmodule")
 		self.auxdb = {}
Index: pym/portage/__init__.py
===================================================================
--- pym/portage/__init__.py	(revision 13324)
+++ pym/portage/__init__.py	(revision 13325)
@@ -987,6 +987,13 @@
 	regex = regex.replace("\\.\\*", ".*")
 	return regex
 
+class _local_repo_config(object):
+	__slots__ = ('eclass_overrides', 'name',)
+	def __init__(self, name, repo_opts):
+		self.name = name
+		self.eclass_overrides = \
+			tuple(repo_opts.get('eclass-overrides', '').split())
+
 class config(object):
 	"""
 	This class encompasses the main portage configuration.  Data is pulled from
@@ -1180,12 +1187,18 @@
 
 		self.user_profile_dir = None
 		self.local_config = local_config
+		self._local_repo_configs = None
+		self._local_repo_conf_path = None
 
 		if clone:
 			self.incrementals = copy.deepcopy(clone.incrementals)
 			self.profile_path = copy.deepcopy(clone.profile_path)
 			self.user_profile_dir = copy.deepcopy(clone.user_profile_dir)
 			self.local_config = copy.deepcopy(clone.local_config)
+			self._local_repo_configs = \
+				copy.deepcopy(clone._local_repo_configs)
+			self._local_repo_conf_path = \
+				copy.deepcopy(clone._local_repo_conf_path)
 
 			self.module_priority = copy.deepcopy(clone.module_priority)
 			self.modules         = copy.deepcopy(clone.modules)
@@ -1628,6 +1641,38 @@
 						self._plicensedict[cp] = cp_dict
 					cp_dict[k] = self.expandLicenseTokens(v)
 
+				self._local_repo_configs = {}
+				self._local_repo_conf_path = \
+					os.path.join(abs_user_config, 'repos.conf')
+				from ConfigParser import SafeConfigParser, ParsingError
+				repo_conf_parser = SafeConfigParser()
+				try:
+					repo_conf_parser.readfp(
+						codecs.open(self._local_repo_conf_path,
+						mode='r', errors='replace'))
+				except EnvironmentError, e:
+					if e.errno != errno.ENOENT:
+						raise
+					del e
+				except ParsingError, e:
+					portage.util.writemsg_level(
+						"!!! Error parsing '%s': %s\n"  % \
+						(self._local_repo_conf_path, e),
+						level=logging.ERROR, noiselevel=-1)
+					del e
+				else:
+					repo_defaults = repo_conf_parser.defaults()
+					if repo_defaults:
+						self._local_repo_configs['DEFAULT'] = \
+							_local_repo_config('DEFAULT', repo_defaults)
+					for repo_name in repo_conf_parser.sections():
+						repo_opts = repo_defaults.copy()
+						for opt_name in repo_conf_parser.options(repo_name):
+							repo_opts[opt_name] = \
+								repo_conf_parser.get(repo_name, opt_name)
+						self._local_repo_configs[repo_name] = \
+							_local_repo_config(repo_name, repo_opts)
+
 			#getting categories from an external file now
 			categories = [grabfile(os.path.join(x, "categories")) for x in locations]
 			self.categories = tuple(sorted(
Index: man/portage.5
===================================================================
--- man/portage.5	(revision 13324)
+++ man/portage.5	(revision 13325)
@@ -54,6 +54,7 @@
 package.use
 mirrors
 categories
+repos.conf
 .fi
 .TP
 .BR /etc/portage/profile/
@@ -546,6 +547,27 @@
 # disable mysql support for QT
 x11\-libs/qt \-mysql
 .fi
+.TP
+.BR repos.conf
+Specifies \fIsite\-specific\fR repository configuration information. Note that
+configuration settings which are specified here do not apply to tools
+such as \fBrepoman\fR(1) and \fBegencache\fR(1) since their operations
+are inherently \fBnot\fR \fIsite\-specific\fR. Beware that use of
+\fBeclass\-overrides\fR is generally not recommended and that it may trigger
+performance issues under some circumstances (see \fBbug #124041\fR).
+
+.I Example:
+.nf
+# make all repositories inherit eclasses from the java\-overlay and
+# java\-experimental repositories, with eclasses from java\-experimental
+# taking precedence over those from java\-overlay
+[DEFAULT]
+eclass\-overrides = java\-overlay java\-experimental
+
+# disable all eclass overrides for ebuilds from the gentoo repository
+[gentoo]
+eclass\-overrides =
+.fi
 .RE
 .TP
 .BR /usr/portage/metadata/