diff -r 5841920d1ef6 Lib/_win_console.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Lib/_win_console.py	Wed Oct 19 22:54:50 2011 +0200
@@ -0,0 +1,147 @@
+import ctypes
+import io
+import sys
+from ctypes import WINFUNCTYPE, windll, POINTER, byref
+from ctypes.wintypes import BOOL, HANDLE, DWORD, LPCSTR, LPWSTR, LPVOID
+
+KERNEL32 = windll.kernel32
+
+INVALID_HANDLE_VALUE = DWORD(-1).value
+STD_OUTPUT_HANDLE = DWORD(-11)
+STD_ERROR_HANDLE  = DWORD(-12)
+FILE_TYPE_CHAR   = 0x0002
+FILE_TYPE_REMOTE = 0x8000
+STDOUT_FILENO = 1
+STDERR_FILENO = 2
+
+GetStdHandle = WINFUNCTYPE(HANDLE, DWORD)(("GetStdHandle", KERNEL32))
+GetFileType = WINFUNCTYPE(DWORD, DWORD)(("GetFileType", KERNEL32))
+GetConsoleMode = WINFUNCTYPE(BOOL, HANDLE, POINTER(DWORD)) \
+                     (("GetConsoleMode", KERNEL32))
+WriteConsoleA = WINFUNCTYPE(BOOL, HANDLE, LPCSTR, DWORD, POINTER(DWORD), \
+                            LPVOID)(("WriteConsoleA", KERNEL32))
+WriteConsoleW = WINFUNCTYPE(BOOL, HANDLE, LPWSTR, DWORD, POINTER(DWORD), \
+                            LPVOID)(("WriteConsoleW", KERNEL32))
+
+class BytesConsole(io.RawIOBase):
+    def __init__(self, hConsole, fileno):
+        self._fileno = fileno
+        self.softspace = False
+        self.mode = 'w'
+        self._hConsole = hConsole
+        io.RawIOBase.__init__(self)
+
+    def flush(self):
+        pass
+
+    def isatty(self):
+        return True
+
+    def fileno(self):
+        return self._fileno
+
+    def writable(self):
+        return True
+
+    def write(self, raw):
+        written = len(raw)
+        while raw:
+            # Issue #11395: the Windows console returns an error (12: not
+            # enough space error) on writing into stdout if stdout mode is
+            # binary and the length is greater than 66,000 bytes (or less,
+            # depending on heap usage).
+            chunk_len = min(len(raw), 32767)
+            chunk = raw[:chunk_len]
+            if not isinstance(chunk, bytes):
+                chunk = bytes(chunk)
+
+            retval = WriteConsoleA(self._hConsole,
+                                   chunk, len(chunk),
+                                   None, None)
+            if retval == 0:
+                raise IOError("WriteConsoleA returned %r" % retval)
+            raw = raw[len(chunk):]
+        return written
+
+class UnicodeConsole(io.TextIOBase):
+    def __init__(self, buffer, hConsole, fileno):
+        io.TextIOBase.__init__(self)
+        self._fileno = fileno
+        self.softspace = False
+        self.mode = 'w'
+        self._hConsole = hConsole
+        self.buffer = buffer
+        self.newline = '\r\n'
+
+    def flush(self):
+        pass
+
+    def isatty(self):
+        return True
+
+    def fileno(self):
+        return self._fileno
+
+    def write(self, text):
+        text = text.replace('\n', self.newline)
+        while text:
+            # Issue #11395: the Windows console returns an error (12: not
+            # enough space error) on writing into stdout if stdout mode is
+            # binary and the length is greater than 66,000 bytes (or less,
+            # depending on heap usage).
+            chunk_len = min(len(text), 32767)
+            chunk = text[:chunk_len]
+
+            retval = WriteConsoleW(self._hConsole,
+                                   chunk, len(chunk),
+                                   None, None)
+            if retval == 0:
+                raise IOError("WriteConsoleW returned %r" % retval)
+            text = text[len(chunk):]
+
+def is_a_console(handle):
+    if handle == INVALID_HANDLE_VALUE or handle is None:
+        return False
+    if (GetFileType(handle) & ~FILE_TYPE_REMOTE) != FILE_TYPE_CHAR:
+        return False
+    mode = DWORD()
+    if GetConsoleMode(handle, byref(mode)) == 0:
+        return False
+    return True
+
+def install_unicode_console():
+    # Make Unicode console output work independently of the current code page.
+    Py_UnbufferedStdioFlag = False
+
+    real_stdout = False
+    if sys.stdout.fileno() == STDOUT_FILENO:
+        hStdout = GetStdHandle(STD_OUTPUT_HANDLE)
+        if is_a_console(hStdout):
+            real_stdout = True
+
+    if real_stdout:
+        sys.stdout.flush()
+        raw = BytesConsole(hStdout, STDOUT_FILENO)
+        if not Py_UnbufferedStdioFlag:
+            buffer = io.BufferedWriter(raw)   # use the default buffer size
+        else:
+            buffer = raw
+        textio = UnicodeConsole(buffer, hStdout, STDOUT_FILENO)
+        sys.stdout = textio
+
+    real_stderr = False
+    if sys.stderr.fileno() == STDERR_FILENO:
+        hStderr = GetStdHandle(STD_ERROR_HANDLE)
+        if is_a_console(hStderr):
+            real_stderr = True
+
+    if real_stderr:
+        sys.stderr.flush()
+        raw = BytesConsole(hStderr, STDERR_FILENO)
+        if not Py_UnbufferedStdioFlag:
+            buffer = io.BufferedWriter(raw)   # use the default buffer size
+        else:
+            buffer = raw
+        textio = UnicodeConsole(buffer, hStderr, STDERR_FILENO)
+        sys.stderr = textio
+
diff -r 5841920d1ef6 Lib/site.py
--- a/Lib/site.py	Tue Oct 18 21:46:37 2011 +0200
+++ b/Lib/site.py	Wed Oct 19 22:54:50 2011 +0200
@@ -530,6 +530,9 @@
     execsitecustomize()
     if ENABLE_USER_SITE:
         execusercustomize()
+    if sys.platform == 'win32':
+        from _win_console import install_unicode_console
+        install_unicode_console()
 
 # Prevent edition of sys.path when python was started with -S and
 # site is imported later.
diff -r 5841920d1ef6 Modules/_io/fileio.c
--- a/Modules/_io/fileio.c	Tue Oct 18 21:46:37 2011 +0200
+++ b/Modules/_io/fileio.c	Wed Oct 19 22:54:50 2011 +0200
@@ -741,14 +741,7 @@
         errno = 0;
         len = pbuf.len;
 #if defined(MS_WIN64) || defined(MS_WINDOWS)
-        if (len > 32767 && isatty(self->fd)) {
-            /* Issue #11395: the Windows console returns an error (12: not
-               enough space error) on writing into stdout if stdout mode is
-               binary and the length is greater than 66,000 bytes (or less,
-               depending on heap usage). */
-            len = 32767;
-        }
-        else if (len > INT_MAX)
+        if (len > INT_MAX)
             len = INT_MAX;
         n = write(self->fd, pbuf.buf, (int)len);
 #else