diff -r 6ea8b8671f73 Doc/library/fileinput.rst
--- a/Doc/library/fileinput.rst	Wed Aug 21 21:52:50 2013 +0300
+++ b/Doc/library/fileinput.rst	Thu Aug 22 10:12:45 2013 +0300
@@ -143,7 +143,8 @@
    sequential order; random access and :meth:`readline` cannot be mixed.
 
    With *mode* you can specify which file mode will be passed to :func:`open`. It
-   must be one of ``'r'``, ``'rU'``, ``'U'`` and ``'rb'``.
+   must be one of ``'r'``, ``'rU'``, ``'U'`` and ``'rb'``. ``'rU'`` and ``'U'``
+   modes are deprecated, unneeded in new code and will not be used in new code.
 
    The *openhook*, when given, must be a function that takes two arguments,
    *filename* and *mode*, and returns an accordingly opened file-like object. You
diff -r 6ea8b8671f73 Doc/library/functions.rst
--- a/Doc/library/functions.rst	Wed Aug 21 21:52:50 2013 +0300
+++ b/Doc/library/functions.rst	Thu Aug 22 10:12:45 2013 +0300
@@ -872,7 +872,7 @@
    ``'b'``   binary mode
    ``'t'``   text mode (default)
    ``'+'``   open a disk file for updating (reading and writing)
-   ``'U'``   universal newlines mode (for backwards compatibility; should
+   ``'U'``   universal newlines mode (deprecated; unneeded in new code; should
              not be used in new code)
    ========= ===============================================================
 
diff -r 6ea8b8671f73 Doc/library/zipfile.rst
--- a/Doc/library/zipfile.rst	Wed Aug 21 21:52:50 2013 +0300
+++ b/Doc/library/zipfile.rst	Thu Aug 22 10:12:45 2013 +0300
@@ -206,9 +206,10 @@
    is the name of the file in the archive, or a :class:`ZipInfo` object. The
    *mode* parameter, if included, must be one of the following: ``'r'`` (the
    default), ``'U'``, or ``'rU'``. Choosing ``'U'`` or  ``'rU'`` will enable
-   :term:`universal newlines` support in the read-only object.  *pwd* is the
-   password used for encrypted files.  Calling  :meth:`.open` on a closed
-   ZipFile will raise a  :exc:`RuntimeError`.
+   :term:`universal newlines` support in the read-only object (deprecated;
+   should not be used in new code; use :class:`io.TextWrapper` for reading
+   compressed text files).  *pwd* is the password used for encrypted files.
+   Calling :meth:`.open` on a closed ZipFile will raise a  :exc:`RuntimeError`.
 
    .. note::
 
diff -r 6ea8b8671f73 Lib/_pyio.py
--- a/Lib/_pyio.py	Wed Aug 21 21:52:50 2013 +0300
+++ b/Lib/_pyio.py	Thu Aug 22 10:12:45 2013 +0300
@@ -62,8 +62,8 @@
     'b'       binary mode
     't'       text mode (default)
     '+'       open a disk file for updating (reading and writing)
-    'U'       universal newline mode (for backwards compatibility; unneeded
-              for new code)
+    'U'       universal newline mode (deprecated; unneeded for new code; should
+              not be used in new code)
     ========= ===============================================================
 
     The default mode is 'rt' (open for reading text). For binary random
@@ -172,6 +172,8 @@
     if "U" in modes:
         if creating or writing or appending:
             raise ValueError("can't use U and writing mode at once")
+        warnings.warn("Use of 'U' mode is deprecated",
+                      DeprecationWarning)
         reading = True
     if text and binary:
         raise ValueError("can't have text and binary mode at once")
diff -r 6ea8b8671f73 Lib/fileinput.py
--- a/Lib/fileinput.py	Wed Aug 21 21:52:50 2013 +0300
+++ b/Lib/fileinput.py	Thu Aug 22 10:12:45 2013 +0300
@@ -222,6 +222,9 @@
         if mode not in ('r', 'rU', 'U', 'rb'):
             raise ValueError("FileInput opening mode must be one of "
                              "'r', 'rU', 'U' and 'rb'")
+        if 'U' in mode:
+            warnings.warn("Use of 'U' mode is deprecated",
+                          DeprecationWarning)
         self._mode = mode
         if openhook:
             if inplace:
diff -r 6ea8b8671f73 Lib/imp.py
--- a/Lib/imp.py	Wed Aug 21 21:52:50 2013 +0300
+++ b/Lib/imp.py	Thu Aug 22 10:12:45 2013 +0300
@@ -103,7 +103,7 @@
 def get_suffixes():
     """**DEPRECATED**"""
     extensions = [(s, 'rb', C_EXTENSION) for s in machinery.EXTENSION_SUFFIXES]
-    source = [(s, 'U', PY_SOURCE) for s in machinery.SOURCE_SUFFIXES]
+    source = [(s, 'r', PY_SOURCE) for s in machinery.SOURCE_SUFFIXES]
     bytecode = [(s, 'rb', PY_COMPILED) for s in machinery.BYTECODE_SUFFIXES]
 
     return extensions + source + bytecode
@@ -274,7 +274,7 @@
         raise ImportError(_ERR_MSG.format(name), name=name)
 
     encoding = None
-    if mode == 'U':
+    if 'b' not in mode:
         with open(file_path, 'rb') as file:
             encoding = tokenize.detect_encoding(file.readline)[0]
     file = open(file_path, mode, encoding=encoding)
diff -r 6ea8b8671f73 Lib/zipfile.py
--- a/Lib/zipfile.py	Wed Aug 21 21:52:50 2013 +0300
+++ b/Lib/zipfile.py	Thu Aug 22 10:12:45 2013 +0300
@@ -1108,8 +1108,11 @@
 
     def open(self, name, mode="r", pwd=None):
         """Return file-like object for 'name'."""
+        if 'U' in mode:
+            warnings.warn("Use of 'U' mode is deprecated",
+                          DeprecationWarning)
         if mode not in ("r", "U", "rU"):
-            raise RuntimeError('open() requires mode "r", "U", or "rU"')
+            raise RuntimeError('open() requires mode "r"')
         if pwd and not isinstance(pwd, bytes):
             raise TypeError("pwd: expected bytes, got %s" % type(pwd))
         if not self.fp:
diff -r 6ea8b8671f73 Modules/_io/_iomodule.c
--- a/Modules/_io/_iomodule.c	Wed Aug 21 21:52:50 2013 +0300
+++ b/Modules/_io/_iomodule.c	Thu Aug 22 10:12:45 2013 +0300
@@ -126,8 +126,8 @@
 "'b'       binary mode\n"
 "'t'       text mode (default)\n"
 "'+'       open a disk file for updating (reading and writing)\n"
-"'U'       universal newline mode (for backwards compatibility; unneeded\n"
-"          for new code)\n"
+"'U'       universal newline mode (deprecated; unneeded for new code; should\n"
+"          not be used in new code)\n"
 "========= ===============================================================\n"
 "\n"
 "The default mode is 'rt' (open for reading text). For binary random\n"
@@ -310,6 +310,9 @@
                             "can't use U and writing mode at once");
             return NULL;
         }
+        if (PyErr_WarnEx(PyExc_DeprecationWarning,
+                         "Use of 'U' mode is deprecated", 1) < 0)
+            return NULL;
         reading = 1;
     }
 
diff -r 6ea8b8671f73 Tools/iobench/iobench.py
--- a/Tools/iobench/iobench.py	Wed Aug 21 21:52:50 2013 +0300
+++ b/Tools/iobench/iobench.py	Thu Aug 22 10:12:45 2013 +0300
@@ -7,6 +7,7 @@
 import re
 import sys
 import time
+import io
 from optparse import OptionParser
 
 out = sys.stdout
@@ -24,6 +25,8 @@
     try:
         return open(fn, mode, encoding=encoding or TEXT_ENCODING)
     except TypeError:
+        if 'r' in mode:
+            mode += 'U'
         return open(fn, mode)
 
 def get_file_sizes():
@@ -380,7 +383,7 @@
             f.write(os.urandom(size))
     # Text files
     chunk = []
-    with text_open(__file__, "rU", encoding='utf8') as f:
+    with text_open(__file__, "r", encoding='utf8') as f:
         for line in f:
             if line.startswith("# <iobench text chunk marker>"):
                 break
diff -r 6ea8b8671f73 Tools/scripts/diff.py
--- a/Tools/scripts/diff.py	Wed Aug 21 21:52:50 2013 +0300
+++ b/Tools/scripts/diff.py	Thu Aug 22 10:12:45 2013 +0300
@@ -38,9 +38,9 @@
 
     fromdate = file_mtime(fromfile)
     todate = file_mtime(tofile)
-    with open(fromfile, 'U') as ff:
+    with open(fromfile, 'r') as ff:
         fromlines = ff.readlines()
-    with open(tofile, 'U') as tf:
+    with open(tofile, 'r') as tf:
         tolines = tf.readlines()
 
     if options.u:
diff -r 6ea8b8671f73 Tools/scripts/ndiff.py
--- a/Tools/scripts/ndiff.py	Wed Aug 21 21:52:50 2013 +0300
+++ b/Tools/scripts/ndiff.py	Thu Aug 22 10:12:45 2013 +0300
@@ -60,7 +60,7 @@
 # couldn't be opened
 def fopen(fname):
     try:
-        return open(fname, 'U')
+        return open(fname, 'r')
     except IOError as detail:
         return fail("couldn't open " + fname + ": " + str(detail))