diff --git a/django/db/backends/__init__.py b/django/db/backends/__init__.py
index 9eb9729ea7..353eb39488 100644
--- a/django/db/backends/__init__.py
+++ b/django/db/backends/__init__.py
@@ -404,7 +404,7 @@ class BaseDatabaseIntrospection(object):
                 tables.add(model._meta.db_table)
                 tables.update([f.m2m_db_table() for f in model._meta.local_many_to_many])
         if only_existing:
-            tables = [t for t in tables if t in self.table_names()]
+            tables = [t for t in tables if self.table_name_converter(t) in self.table_names()]
         return tables
 
     def installed_models(self, tables):
diff --git a/django/db/models/fields/related.py b/django/db/models/fields/related.py
index 1763bf2523..c87b823a69 100644
--- a/django/db/models/fields/related.py
+++ b/django/db/models/fields/related.py
@@ -1,4 +1,5 @@
 from django.db import connection, transaction
+from django.db.backends import util
 from django.db.models import signals, get_model
 from django.db.models.fields import AutoField, Field, IntegerField, PositiveIntegerField, PositiveSmallIntegerField, FieldDoesNotExist
 from django.db.models.related import RelatedObject
@@ -771,7 +772,8 @@ class ManyToManyField(RelatedField, Field):
         elif self.db_table:
             return self.db_table
         else:
-            return '%s_%s' % (opts.db_table, self.name)
+            return util.truncate_name('%s_%s' % (opts.db_table, self.name),
+                                      connection.ops.max_name_length())
 
     def _get_m2m_column_name(self, related):
         "Function that can be curried to provide the source column name for the m2m table"