Index: Objects/longobject.c
===================================================================
--- Objects/longobject.c	(revision 69488)
+++ Objects/longobject.c	(working copy)
@@ -557,7 +557,7 @@
 	if (Py_SIZE(v) < 0) {
 		ndigits = -(Py_SIZE(v));
 		if (!is_signed) {
-			PyErr_SetString(PyExc_TypeError,
+			PyErr_SetString(PyExc_OverflowError,
 				"can't convert negative long to unsigned");
 			return -1;
 		}
Index: Doc/c-api/long.rst
===================================================================
--- Doc/c-api/long.rst	(revision 69488)
+++ Doc/c-api/long.rst	(working copy)
@@ -155,22 +155,32 @@
 
 .. cfunction:: PY_LONG_LONG PyLong_AsLongLong(PyObject *pylong)
 
+   .. index::
+      single: OverflowError (built-in exception)
+
    Return a C :ctype:`long long` from a Python long integer.  If *pylong* cannot be
-   represented as a :ctype:`long long`, an :exc:`OverflowError` will be raised.
+   represented as a :ctype:`long long`, an :exc:`OverflowError` is raised and
+   ``-1`` is returned.
 
    .. versionadded:: 2.2
 
 
 .. cfunction:: unsigned PY_LONG_LONG PyLong_AsUnsignedLongLong(PyObject *pylong)
 
-   Return a C :ctype:`unsigned long long` from a Python long integer. If *pylong*
-   cannot be represented as an :ctype:`unsigned long long`, an :exc:`OverflowError`
-   will be raised if the value is positive, or a :exc:`TypeError` will be raised if
-   the value is negative.
+   .. index::
+      single: OverflowError (built-in exception)
 
+   Return a C :ctype:`unsigned long long` from a Python long integer. If
+   *pylong* cannot be represented as an :ctype:`unsigned long long`, an
+   :exc:`OverflowError` is raised and ``(unsigned long long)-1`` is
+   returned.
+
    .. versionadded:: 2.2
 
+   .. versionchanged:: 2.7
+      A negative *pylong* now raises :exc:`OverflowError`, not :exc:`TypeError`.
 
+
 .. cfunction:: unsigned long PyLong_AsUnsignedLongMask(PyObject *io)
 
    Return a C :ctype:`unsigned long` from a Python long integer, without checking
Index: Lib/test/test_struct.py
===================================================================
--- Lib/test/test_struct.py	(revision 69488)
+++ Lib/test/test_struct.py	(working copy)
@@ -48,7 +48,7 @@
 def deprecated_err(func, *args):
     try:
         func(*args)
-    except (struct.error, TypeError):
+    except (struct.error, OverflowError):
         pass
     except DeprecationWarning:
         if not PY_STRUCT_OVERFLOW_MASKING:
@@ -185,7 +185,7 @@
 
     def test_native_qQ(self):
         # can't pack -1 as unsigned regardless
-        self.assertRaises((struct.error, TypeError), struct.pack, "Q", -1)
+        self.assertRaises((struct.error, OverflowError), struct.pack, "Q", -1)
         # can't pack string as 'q' regardless
         self.assertRaises(struct.error, struct.pack, "q", "a")
         # ditto, but 'Q'
Index: Modules/testcapi_long.h
===================================================================
--- Modules/testcapi_long.h	(revision 69488)
+++ Modules/testcapi_long.h	(working copy)
@@ -97,6 +97,10 @@
 		if (uout != (unsigned TYPENAME)-1 || !PyErr_Occurred())
 			return error(
 				"PyLong_AsUnsignedXXX(-1) didn't complain");
+		if (!PyErr_ExceptionMatches(PyExc_OverflowError))
+			return error(
+				"PyLong_AsUnsignedXXX(-1) raised "
+				"something other than OverflowError");
 		PyErr_Clear();
 		UNBIND(x);
 
@@ -117,6 +121,10 @@
 			return error(
 				"PyLong_AsUnsignedXXX(2**NBITS) didn't "
 				"complain");
+		if (!PyErr_ExceptionMatches(PyExc_OverflowError))
+			return error(
+				"PyLong_AsUnsignedXXX(2**NBITS) raised "
+				"something other than OverflowError");
 		PyErr_Clear();
 
 		/* Signed complains about 2**(NBITS-1)?
@@ -132,6 +140,10 @@
 			return error(
 				"PyLong_AsXXX(2**(NBITS-1)) didn't "
 				"complain");
+		if (!PyErr_ExceptionMatches(PyExc_OverflowError))
+			return error(
+				"PyLong_AsXXX(2**(NBITS-1)) raised "
+				"something other than OverflowError");
 		PyErr_Clear();
 
 		/* Signed complains about -2**(NBITS-1)-1?;
@@ -153,6 +165,10 @@
 			return error(
 				"PyLong_AsXXX(-2**(NBITS-1)-1) didn't "
 				"complain");
+		if (!PyErr_ExceptionMatches(PyExc_OverflowError))
+			return error(
+				"PyLong_AsXXX(-2**(NBITS-1)-1) raised "
+				"something other than OverflowError");
 		PyErr_Clear();
 		UNBIND(y);