diff -r 52b05cedb7c3 Lib/inspect.py
--- a/Lib/inspect.py	Wed May 20 14:38:50 2015 -0400
+++ b/Lib/inspect.py	Wed May 20 17:02:48 2015 -0400
@@ -2661,11 +2661,17 @@
     @classmethod
     def from_function(cls, func):
         """Constructs Signature for the given python function."""
+
+        warnings.warn("inspect.Signature.from_function() is deprecated, "
+                      "use Signature.from_callback()", DeprecationWarning)
         return _signature_from_function(cls, func)
 
     @classmethod
     def from_builtin(cls, func):
         """Constructs Signature for the given builtin function."""
+
+        warnings.warn("inspect.Signature.from_builtin() is deprecated, "
+                      "use Signature.from_callback()", DeprecationWarning)
         return _signature_from_builtin(cls, func)
 
     @classmethod
diff -r 52b05cedb7c3 Lib/test/test_inspect.py
--- a/Lib/test/test_inspect.py	Wed May 20 14:38:50 2015 -0400
+++ b/Lib/test/test_inspect.py	Wed May 20 17:02:48 2015 -0400
@@ -1971,13 +1971,6 @@
         with self.assertRaisesRegex(TypeError, 'is not a callable object'):
             inspect.signature(42)
 
-        with self.assertRaisesRegex(TypeError, 'is not a Python function'):
-            inspect.Signature.from_function(42)
-
-    def test_signature_from_builtin_errors(self):
-        with self.assertRaisesRegex(TypeError, 'is not a Python builtin'):
-            inspect.Signature.from_builtin(42)
-
     def test_signature_from_functionlike_object(self):
         def func(a,b, *args, kwonly=True, kwonlyreq, **kwargs):
             pass
@@ -1998,9 +1991,9 @@
             def __call__(self, *args, **kwargs):
                 return self.func(*args, **kwargs)
 
-        sig_func = inspect.Signature.from_function(func)
-
-        sig_funclike = inspect.Signature.from_function(funclike(func))
+        sig_func = inspect.Signature.from_callable(func)
+
+        sig_funclike = inspect.Signature.from_callable(funclike(func))
         self.assertEqual(sig_funclike, sig_func)
 
         sig_funclike = inspect.signature(funclike(func))
@@ -2048,9 +2041,6 @@
             __defaults__ = func.__defaults__
             __kwdefaults__ = func.__kwdefaults__
 
-        with self.assertRaisesRegex(TypeError, 'is not a Python function'):
-            inspect.Signature.from_function(funclike)
-
         self.assertEqual(str(inspect.signature(funclike)), '(marker)')
 
     def test_signature_on_method(self):