Index: Lib/ntpath.py
===================================================================
--- Lib/ntpath.py	(revision 69123)
+++ Lib/ntpath.py	(working copy)
@@ -468,13 +468,20 @@
 supports_unicode_filenames = (hasattr(sys, "getwindowsversion") and
                               sys.getwindowsversion()[3] >= 2)
 
+# _abspath_split('d:\\') should return ['d:'] instead of ['d:', '']
+def _abspath_split(path):
+    path_list = abspath(path).split(sep)
+    if path_list and not path_list[-1]:
+        del path_list[-1]
+    return path_list
+
 def relpath(path, start=curdir):
     """Return a relative version of a path"""
 
     if not path:
         raise ValueError("no path specified")
-    start_list = abspath(start).split(sep)
-    path_list = abspath(path).split(sep)
+    start_list = _abspath_split(start)
+    path_list = _abspath_split(path)
     if start_list[0].lower() != path_list[0].lower():
         unc_path, rest = splitunc(path)
         unc_start, rest = splitunc(start)
Index: Lib/posixpath.py
===================================================================
--- Lib/posixpath.py	(revision 69123)
+++ Lib/posixpath.py	(working copy)
@@ -386,14 +386,21 @@
 
 supports_unicode_filenames = False
 
+# _abspath_split('/') should return [''] instead of ['', '']
+def _abspath_split(path):
+    path_list = abspath(path).split(sep)
+    if path_list and not path_list[-1]:
+        del path_list[-1]
+    return path_list
+
 def relpath(path, start=curdir):
     """Return a relative version of a path"""
 
     if not path:
         raise ValueError("no path specified")
 
-    start_list = abspath(start).split(sep)
-    path_list = abspath(path).split(sep)
+    start_list = _abspath_split(start)
+    path_list = _abspath_split(path)
 
     # Work out how much of the filepath is shared by start and path.
     i = len(commonprefix([start_list, path_list]))
Index: Lib/test/test_ntpath.py
===================================================================
--- Lib/test/test_ntpath.py	(revision 69123)
+++ Lib/test/test_ntpath.py	(working copy)
@@ -177,8 +177,11 @@
         tester('ntpath.relpath("a", "b/c")', '..\\..\\a')
         tester('ntpath.relpath("//conky/mountpoint/a", "//conky/mountpoint/b/c")', '..\\..\\a')
         tester('ntpath.relpath("a", "a")', '.')
+        tester('ntpath.relpath("d:/a", "d:/")', 'a')
+        tester('ntpath.relpath("d:/a", "d:/b")', '..\\a')
+        tester('ntpath.relpath("d:/a", "d:/a/b")', '..')
+        tester('ntpath.relpath("d:/a/b", "d:/a")', 'b')
 
-
 def test_main():
     test_support.run_unittest(TestNtpath)
 
Index: Lib/test/test_posixpath.py
===================================================================
--- Lib/test/test_posixpath.py	(revision 69123)
+++ Lib/test/test_posixpath.py	(working copy)
@@ -502,6 +502,10 @@
             self.assertEqual(posixpath.relpath("a/b", "../c"), "../"+curdir+"/a/b")
             self.assertEqual(posixpath.relpath("a", "b/c"), "../../a")
             self.assertEqual(posixpath.relpath("a", "a"), ".")
+            self.assertEqual(posixpath.relpath("/a", "/"), "a")
+            self.assertEqual(posixpath.relpath("/a", "/b"), "../a")
+            self.assertEqual(posixpath.relpath("/a", "/a/b"), "..")
+            self.assertEqual(posixpath.relpath("/a/b", "/a"), "b")
         finally:
             os.getcwd = real_getcwd