diff --git a/django/conf/global_settings.py b/django/conf/global_settings.py
index 0017f46708..dad5097620 100644
--- a/django/conf/global_settings.py
+++ b/django/conf/global_settings.py
@@ -436,7 +436,6 @@ CACHES = {
 }
 # The cache backend to use.  See the docstring in django.core.cache for the
 # possible values.
-CACHE_BACKEND = 'locmem://'
 CACHE_MIDDLEWARE_KEY_PREFIX = ''
 CACHE_MIDDLEWARE_SECONDS = 600
 CACHE_MIDDLEWARE_ALIAS = 'default'
diff --git a/django/core/cache/__init__.py b/django/core/cache/__init__.py
index ced9875b07..2c75f6c671 100644
--- a/django/core/cache/__init__.py
+++ b/django/core/cache/__init__.py
@@ -75,11 +75,21 @@ def parse_backend_uri(backend_uri):
     return scheme, host, params
 
 if not settings.CACHES:
-    import warnings
-    warnings.warn(
-        "settings.CACHE_* is deprecated; use settings.CACHES instead.",
-        PendingDeprecationWarning
-    )
+    legacy_backend = getattr(settings, 'CACHE_BACKEND', None)
+    if legacy_backend:
+        import warnings
+        warnings.warn(
+            "settings.CACHE_* is deprecated; use settings.CACHES instead.",
+            PendingDeprecationWarning
+        )
+    else:
+        # The default cache setting is put here so that we
+        # can differentiate between a user who has provided
+        # an explicit CACHE_BACKEND of locmem://, and the
+        # default value. When the deprecation cycle has completed,
+        # the default can be restored to global_settings.py
+        settings.CACHE_BACKEND = 'locmem://'
+
     # Mapping for new-style cache backend api
     backend_classes = {
         'memcached': 'memcached.CacheClass',