diff --git a/cms/djangoapps/contentstore/tests/test_crud.py b/cms/djangoapps/contentstore/tests/test_crud.py
index a16251fa0f..b95d58d913 100644
--- a/cms/djangoapps/contentstore/tests/test_crud.py
+++ b/cms/djangoapps/contentstore/tests/test_crud.py
@@ -2,7 +2,7 @@ import unittest
 from xmodule import templates
 from xmodule.modulestore.tests import persistent_factories
 from xmodule.course_module import CourseDescriptor
-from xmodule.modulestore.django import modulestore
+from xmodule.modulestore.django import modulestore, loc_mapper
 from xmodule.seq_module import SequenceDescriptor
 from xmodule.capa_module import CapaDescriptor
 from xmodule.modulestore.locator import CourseLocator, BlockUsageLocator
@@ -191,6 +191,26 @@ class TemplateTests(unittest.TestCase):
         version_history = modulestore('split').get_block_generations(second_problem.location)
         self.assertNotEqual(version_history.locator.version_guid, first_problem.location.version_guid)
 
+    def test_split_inject_loc_mapper(self):
+        """
+        Test that creating a loc_mapper causes it to automatically attach to the split mongo store
+        """
+        # instantiate location mapper before split
+        mapper = loc_mapper()
+        # split must inject the location mapper itself since the mapper existed before it did
+        self.assertEqual(modulestore('split').loc_mapper, mapper)
+
+    def test_loc_inject_into_split(self):
+        """
+        Test that creating a loc_mapper causes it to automatically attach to the split mongo store
+        """
+        # force instantiation of split modulestore before there's a location mapper and verify
+        # it has no pointer to loc mapper
+        self.assertIsNone(modulestore('split').loc_mapper)
+        # force instantiation of location mapper which must inject itself into the split
+        mapper = loc_mapper()
+        self.assertEqual(modulestore('split').loc_mapper, mapper)
+
     # ================================= JSON PARSING ===========================
     # These are example methods for creating xmodules in memory w/o persisting them.
     # They were in x_module but since xblock is not planning to support them but will
diff --git a/cms/envs/acceptance.py b/cms/envs/acceptance.py
index bbb767118c..73dc91dbd7 100644
--- a/cms/envs/acceptance.py
+++ b/cms/envs/acceptance.py
@@ -24,14 +24,17 @@ from random import choice, randint
 def seed():
     return os.getppid()
 
-MODULESTORE_OPTIONS = {
-    'default_class': 'xmodule.raw_module.RawDescriptor',
+DOC_STORE_CONFIG = {
     'host': 'localhost',
     'db': 'acceptance_xmodule',
     'collection': 'acceptance_modulestore_%s' % seed(),
+}
+
+MODULESTORE_OPTIONS = dict({
+    'default_class': 'xmodule.raw_module.RawDescriptor',
     'fs_root': TEST_ROOT / "data",
     'render_template': 'mitxmako.shortcuts.render_to_string',
-}
+}, **DOC_STORE_CONFIG)
 
 MODULESTORE = {
     'default': {
@@ -90,6 +93,6 @@ LETTUCE_BROWSER = os.environ.get('LETTUCE_BROWSER', 'chrome')
 #####################################################################
 # Lastly, see if the developer has any local overrides.
 try:
-    from .private import *      # pylint: disable=F0401
+    from .private import *  # pylint: disable=F0401
 except ImportError:
     pass
diff --git a/cms/envs/dev.py b/cms/envs/dev.py
index 42a6f706b6..6e4ce460c3 100644
--- a/cms/envs/dev.py
+++ b/cms/envs/dev.py
@@ -16,14 +16,17 @@ LOGGING = get_logger_config(ENV_ROOT / "log",
                             dev_env=True,
                             debug=True)
 
-modulestore_options = {
-    'default_class': 'xmodule.raw_module.RawDescriptor',
+DOC_STORE_CONFIG = {
     'host': 'localhost',
     'db': 'xmodule',
     'collection': 'modulestore',
+}
+
+modulestore_options = dict({
+    'default_class': 'xmodule.raw_module.RawDescriptor',
     'fs_root': GITHUB_REPO_ROOT,
     'render_template': 'mitxmako.shortcuts.render_to_string',
-}
+}, **DOC_STORE_CONFIG)
 
 MODULESTORE = {
     'default': {
@@ -185,6 +188,6 @@ if SEGMENT_IO_KEY:
 #####################################################################
 # Lastly, see if the developer has any local overrides.
 try:
-    from .private import *      # pylint: disable=F0401
+    from .private import *  # pylint: disable=F0401
 except ImportError:
     pass
diff --git a/cms/envs/test.py b/cms/envs/test.py
index ffbf9f5376..364bee2441 100644
--- a/cms/envs/test.py
+++ b/cms/envs/test.py
@@ -42,14 +42,17 @@ STATICFILES_DIRS += [
     if os.path.isdir(COMMON_TEST_DATA_ROOT / course_dir)
 ]
 
-MODULESTORE_OPTIONS = {
-    'default_class': 'xmodule.raw_module.RawDescriptor',
+DOC_STORE_CONFIG = {
     'host': 'localhost',
     'db': 'test_xmodule',
     'collection': 'test_modulestore',
+}
+
+MODULESTORE_OPTIONS = dict({
+    'default_class': 'xmodule.raw_module.RawDescriptor',
     'fs_root': TEST_ROOT / "data",
     'render_template': 'mitxmako.shortcuts.render_to_string',
-}
+}, **DOC_STORE_CONFIG)
 
 MODULESTORE = {
     'default': {
diff --git a/common/lib/xmodule/xmodule/modulestore/django.py b/common/lib/xmodule/xmodule/modulestore/django.py
index d9176f6abf..284f5e4eb7 100644
--- a/common/lib/xmodule/xmodule/modulestore/django.py
+++ b/common/lib/xmodule/xmodule/modulestore/django.py
@@ -93,7 +93,7 @@ def loc_mapper():
     # pylint: disable=W0212
     if _loc_singleton is None:
         # instantiate
-        _loc_singleton = LocMapperStore(settings.modulestore_options)
+        _loc_singleton = LocMapperStore(**settings.DOC_STORE_CONFIG)
     # inject into split mongo modulestore
     if 'split' in _MODULESTORES:
         _MODULESTORES['split'].loc_mapper = _loc_singleton
diff --git a/common/lib/xmodule/xmodule/modulestore/loc_mapper_store.py b/common/lib/xmodule/xmodule/modulestore/loc_mapper_store.py
index 4ab3a8106d..1b4cee7c95 100644
--- a/common/lib/xmodule/xmodule/modulestore/loc_mapper_store.py
+++ b/common/lib/xmodule/xmodule/modulestore/loc_mapper_store.py
@@ -33,11 +33,6 @@ class LocMapperStore(object):
         '''
         Constructor
         '''
-        # get rid of unwanted args
-        kwargs.pop('default_class', None)
-        kwargs.pop('fs_root', None)
-        kwargs.pop('xblock_mixins', None)
-        kwargs.pop('render_template', None)
         self.db = pymongo.database.Database(
             pymongo.MongoClient(
                 host=host,
diff --git a/common/lib/xmodule/xmodule/modulestore/tests/test_split_migrator.py b/common/lib/xmodule/xmodule/modulestore/tests/test_split_migrator.py
index 86c99f7015..40e1b466c4 100644
--- a/common/lib/xmodule/xmodule/modulestore/tests/test_split_migrator.py
+++ b/common/lib/xmodule/xmodule/modulestore/tests/test_split_migrator.py
@@ -25,19 +25,22 @@ from xmodule.modulestore.mongo import draft
 class TestMigration(unittest.TestCase):
 
     # Snippet of what would be in the django settings envs file
-    modulestore_options = {
-        'default_class': 'xmodule.raw_module.RawDescriptor',
+    db_config = {
         'host': 'localhost',
         'db': 'test_xmodule',
         'collection': 'modulestore{0}'.format(uuid.uuid4().hex),
+    }
+
+    modulestore_options = dict({
+        'default_class': 'xmodule.raw_module.RawDescriptor',
         'fs_root': '',
         'render_template': mock.Mock(return_value=""),
         'xblock_mixins': (InheritanceMixin,)
-    }
+    }, **db_config)
 
     def setUp(self):
         super(TestMigration, self).setUp()
-        self.loc_mapper = LocMapperStore(**self.modulestore_options)
+        self.loc_mapper = LocMapperStore(**self.db_config)
         self.old_mongo = MongoModuleStore(**self.modulestore_options)
         self.draft_mongo = DraftModuleStore(**self.modulestore_options)
         self.split_mongo = SplitMongoModuleStore(
diff --git a/lms/envs/acceptance.py b/lms/envs/acceptance.py
index 2182bbcad6..b261e2be54 100644
--- a/lms/envs/acceptance.py
+++ b/lms/envs/acceptance.py
@@ -26,14 +26,17 @@ def seed():
     return os.getppid()
 
 # Use the mongo store for acceptance tests
-modulestore_options = {
-    'default_class': 'xmodule.raw_module.RawDescriptor',
+DOC_STORE_CONFIG = {
     'host': 'localhost',
     'db': 'acceptance_xmodule',
     'collection': 'acceptance_modulestore_%s' % seed(),
+}
+
+modulestore_options = dict({
+    'default_class': 'xmodule.raw_module.RawDescriptor',
     'fs_root': TEST_ROOT / "data",
     'render_template': 'mitxmako.shortcuts.render_to_string',
-}
+}, **DOC_STORE_CONFIG)
 
 MODULESTORE = {
     'default': {
@@ -129,6 +132,6 @@ LETTUCE_BROWSER = os.environ.get('LETTUCE_BROWSER', 'chrome')
 #####################################################################
 # Lastly, see if the developer has any local overrides.
 try:
-    from .private import *      # pylint: disable=F0401
+    from .private import *  # pylint: disable=F0401
 except ImportError:
     pass
diff --git a/lms/envs/cms/dev.py b/lms/envs/cms/dev.py
index 0d11c373c9..7026d45366 100644
--- a/lms/envs/cms/dev.py
+++ b/lms/envs/cms/dev.py
@@ -22,14 +22,17 @@ MITX_FEATURES['ENABLE_LMS_MIGRATION'] = False
 
 META_UNIVERSITIES = {}
 
-modulestore_options = {
-    'default_class': 'xmodule.raw_module.RawDescriptor',
+DOC_STORE_CONFIG = {
     'host': 'localhost',
     'db': 'xmodule',
     'collection': 'modulestore',
+}
+
+modulestore_options = dict({
+    'default_class': 'xmodule.raw_module.RawDescriptor',
     'fs_root': DATA_DIR,
     'render_template': 'mitxmako.shortcuts.render_to_string',
-}
+}, **DOC_STORE_CONFIG)
 
 MODULESTORE = {
     'default': {