diff --git a/Lib/importlib/__init__.py b/Lib/importlib/__init__.py
--- a/Lib/importlib/__init__.py
+++ b/Lib/importlib/__init__.py
@@ -1,7 +1,15 @@
 """A pure Python implementation of import."""
 __all__ = ['__import__', 'import_module', 'invalidate_caches']
 
-from . import _bootstrap
+
+import sys
+from . import _bootstrap as _pure_bootstrap
+try:
+    import _frozen_importlib as _bootstrap
+    sys.modules['importlib._bootstrap'] = _bootstrap
+except ImportError:
+    _bootstrap = _pure_bootstrap
+
 
 
 # To simplify imports in test code
@@ -9,16 +17,9 @@
 _r_long = _bootstrap._r_long
 
 
-# Bootstrap help #####################################################
-import imp
-import sys
-
-_bootstrap._setup(sys, imp)
-
-
 # Public API #########################################################
 
-from ._bootstrap import __import__
+__import__ = _bootstrap.__import__
 
 
 def invalidate_caches():
diff --git a/Lib/importlib/test/util.py b/Lib/importlib/test/util.py
--- a/Lib/importlib/test/util.py
+++ b/Lib/importlib/test/util.py
@@ -24,6 +24,34 @@
                             "requires a case-insensitive filesystem")(test)
 
 
+def set_bootstrap(importlib, bootstrap):
+    """Set importlib to use the passed bootstrap module."""
+    importlib._w_long = bootstrap._w_long
+    importlib._r_long = bootstrap._r_long
+    importlib._bootstrap = bootstrap
+    importlib.__import__ = bootstrap.__import__
+    sys.modules['importlib._bootstrap'] = bootstrap
+
+
+@contextmanager
+def bootstrap_context(importlib, bootstrap):
+    """Temporarily use an alternate bootstrap module."""
+    old_bootstrap = importlib._bootstrap
+    try:
+        set_bootstrap(importlib, bootstrap)
+        yield
+    finally:
+        set_bootstrap(importlib, old_bootstrap)
+
+
+def pure_bootstrap_context(importlib):
+    """Temporarily use importlib._bootstrap."""
+    # importlib._bootstrap will normally be the same as _frozen_importlib
+    if not hasattr(importlib._pure_bootstrap, 'sys'):
+        importlib._pure_bootstrap._setup(sys, imp)
+    return bootstrap_context(importlib, importlib._pure_bootstrap)
+
+
 @contextmanager
 def uncache(*names):
     """Uncache a module from sys.modules.