diff -r 9d9c2b4850fc Lib/inspect.py
--- a/Lib/inspect.py	Fri Dec 27 14:06:15 2013 -0500
+++ b/Lib/inspect.py	Wed Jan 01 19:19:12 2014 +0400
@@ -2003,7 +2003,6 @@
 
         return cls(parameters, return_annotation=cls.empty)
 
-
     @property
     def parameters(self):
         return self._parameters
diff -r 9d9c2b4850fc Lib/pydoc.py
--- a/Lib/pydoc.py	Fri Dec 27 14:06:15 2013 -0500
+++ b/Lib/pydoc.py	Wed Jan 01 19:19:12 2014 +0400
@@ -928,7 +928,7 @@
                     # So removing parentheses isn't truly safe.
                     argspec = argspec[1:-1] # remove parentheses
         if not argspec:
-            argspec = '(...)'
+            argspec = getattr(object, '__text_signature__', '') or '(...)'
 
         decl = title + argspec + (note and self.grey(
                '<font face="helvetica, arial">%s</font>' % note))
@@ -1323,7 +1323,7 @@
                     # So removing parentheses isn't truly safe.
                     argspec = argspec[1:-1] # remove parentheses
         if not argspec:
-            argspec = '(...)'
+            argspec = getattr(object, '__text_signature__', '') or '(...)'
         decl = title + argspec + note
 
         if skipdocs:
diff -r 9d9c2b4850fc Lib/test/test_capi.py
--- a/Lib/test/test_capi.py	Fri Dec 27 14:06:15 2013 -0500
+++ b/Lib/test/test_capi.py	Wed Jan 01 19:19:12 2014 +0400
@@ -140,6 +140,12 @@
         self.assertEqual(_testcapi.docstring_with_signature_and_extra_newlines.__text_signature__,
             "(parameter)")
 
+        self.assertEqual(_testcapi.docstring_with_multiline_signature.__doc__,
+            "This docstring has a valid signature.")
+
+        self.assertEqual(_testcapi.docstring_with_multiline_signature.__text_signature__,
+        """(parameter1,\n                                   parameter2, kwarg1='a',\n                                   kwarg2='b') -> result""")
+
 
 @unittest.skipUnless(threading, 'Threading required for this test.')
 class TestPendingCalls(unittest.TestCase):
diff -r 9d9c2b4850fc Modules/_testcapimodule.c
--- a/Modules/_testcapimodule.c	Fri Dec 27 14:06:15 2013 -0500
+++ b/Modules/_testcapimodule.c	Wed Jan 01 19:19:12 2014 +0400
@@ -2869,6 +2869,14 @@
 "This docstring has a valid signature and some extra newlines."
 );
 
+PyDoc_STRVAR(docstring_with_multiline_signature,
+"docstring_with_multiline_signature(parameter1,\n"
+"                                   parameter2, kwarg1='a',\n"
+"                                   kwarg2='b') -> result\n"
+"\n"
+"This docstring has a valid signature."
+);
+
 #ifdef WITH_THREAD
 typedef struct {
     PyThread_type_lock start_event;
@@ -3087,6 +3095,9 @@
     {"docstring_with_signature_and_extra_newlines",
         (PyCFunction)test_with_docstring, METH_NOARGS,
         docstring_with_signature_and_extra_newlines},
+    {"docstring_with_multiline_signature",
+        (PyCFunction)test_with_docstring, METH_NOARGS,
+        docstring_with_multiline_signature},
 #ifdef WITH_THREAD
     {"call_in_temporary_c_thread", call_in_temporary_c_thread, METH_O,
      PyDoc_STR("set_error_class(error_class) -> None")},
diff -r 9d9c2b4850fc Objects/methodobject.c
--- a/Objects/methodobject.c	Fri Dec 27 14:06:15 2013 -0500
+++ b/Objects/methodobject.c	Wed Jan 01 19:19:12 2014 +0400
@@ -205,8 +205,17 @@
  */
 static const char *skip_signature(const char *trace)
 {
-    while (*trace && *trace != '\n')
+    int open_parens = 0;
+
+    while (*trace && (*trace != '\n' || open_parens != 0)) {
+        if (*trace == '(')
+            open_parens++;
+        else if (*trace == ')')
+            open_parens--;
+
         trace++;
+    }
+
     return trace;
 }