Index: Lib/email/test/test_email.py
===================================================================
--- Lib/email/test/test_email.py	(revision 87768)
+++ Lib/email/test/test_email.py	(working copy)
@@ -2886,52 +2886,61 @@
                          '<,.V<W1A; á \n'.encode('utf-8'))
 
 
-    headertest_msg = textwrap.dedent("""\
-        From: foo@bar.com
-        To: báz
-        Subject: Maintenant je vous présente mon collègue, le pouf célèbre
-        \tJean de Baddie
-        From: göst
+    headertest_headers = (
+        ('From: foo@bar.com', ('From', 'foo@bar.com')),
+        ('To: báz', ('To', '=?unknown-8bit?q?b=C3=A1z?=')),
+        ('Subject: Maintenant je vous présente mon collègue, le pouf célèbre\n'
+            '\tJean de Baddie',
+            ('Subject', '=?unknown-8bit?q?Maintenant_je_vous_pr=C3=A9sente_mon_coll=C3=A8gue=2C_le_pouf_c=C3=A9l=C3=A8bre?=\n'
+                ' =?unknown-8bit?q?=09Jean_de_Baddie?=')),
+        ('From: göst', ('From', '=?unknown-8bit?b?Z8O2c3Q=?=')),
+        )
+    headertest_msg = ('\n'.join([src for (src, _) in headertest_headers]) + 
+        '\nYes, they are flying.\n').encode('utf-8')
 
-        Yes, they are flying.
-        """).encode('utf-8')
-
     def test_get_8bit_header(self):
         msg = email.message_from_bytes(self.headertest_msg)
-        self.assertEqual(msg.get('to'), 'b??z')
-        self.assertEqual(msg['to'], 'b??z')
+        self.assertEqual(str(msg.get('to')), 'b��z')
+        self.assertEqual(str(msg['to']), 'b��z')
 
     def test_print_8bit_headers(self):
         msg = email.message_from_bytes(self.headertest_msg)
         self.assertEqual(str(msg),
-                         self.headertest_msg.decode(
-                            'ascii', 'replace').replace('�', '?'))
+                         textwrap.dedent("""\
+                            From: {}
+                            To: {}
+                            Subject: {}
+                            From: {}
 
+                            Yes, they are flying.
+                            """).format(*[expected[1] for (_, expected) in
+                                        self.headertest_headers]))
+
     def test_values_with_8bit_headers(self):
         msg = email.message_from_bytes(self.headertest_msg)
-        self.assertListEqual(msg.values(),
+        self.assertListEqual([str(x) for x in msg.values()],
                               ['foo@bar.com',
-                               'b??z',
-                               'Maintenant je vous pr??sente mon '
-                                   'coll??gue, le pouf c??l??bre\n'
+                               'b��z',
+                               'Maintenant je vous pr��sente mon '
+                                   'coll��gue, le pouf c��l��bre\n'
                                    '\tJean de Baddie',
-                               "g??st"])
+                               "g��st"])
 
     def test_items_with_8bit_headers(self):
         msg = email.message_from_bytes(self.headertest_msg)
-        self.assertListEqual(msg.items(),
+        self.assertListEqual([(str(x), str(y)) for (x, y) in msg.items()],
                               [('From', 'foo@bar.com'),
-                               ('To', 'b??z'),
-                               ('Subject', 'Maintenant je vous pr??sente mon '
-                                              'coll??gue, le pouf c??l??bre\n'
+                               ('To', 'b��z'),
+                               ('Subject', 'Maintenant je vous pr��sente mon '
+                                              'coll��gue, le pouf c��l��bre\n'
                                               '\tJean de Baddie'),
-                               ('From', 'g??st')])
+                               ('From', 'g��st')])
 
     def test_get_all_with_8bit_headers(self):
         msg = email.message_from_bytes(self.headertest_msg)
-        self.assertListEqual(msg.get_all('from'),
+        self.assertListEqual([str(x) for x in msg.get_all('from')],
                               ['foo@bar.com',
-                               'g??st'])
+                               'g��st'])
 
     non_latin_bin_msg = textwrap.dedent("""\
         From: foo@bar.com
@@ -2953,11 +2962,12 @@
 
     # XXX: ultimately the '?' should turn into CTE encoded bytes
     # using 'unknown-8bit' charset.
-    non_latin_bin_msg_as7bit = textwrap.dedent("""\
+    non_latin_bin_msg_as7bit_wrapped = textwrap.dedent("""\
         From: foo@bar.com
-        To: b??z
-        Subject: Maintenant je vous pr??sente mon coll??gue, le pouf c??l??bre
-        \tJean de Baddie
+        To: =?unknown-8bit?q?b=C3=A1z?=
+        Subject: =?unknown-8bit?q?Maintenant_je_vous_pr=C3=A9sente_mon_coll=C3=A8gue?=
+         =?unknown-8bit?q?=2C_le_pouf_c=C3=A9l=C3=A8bre?=
+         =?unknown-8bit?q?=09Jean_de_Baddie?=
         Mime-Version: 1.0
         Content-Type: text/plain; charset="utf-8"
         Content-Transfer-Encoding: base64
@@ -2969,7 +2979,7 @@
         msg = email.message_from_bytes(self.non_latin_bin_msg)
         out = StringIO()
         email.generator.Generator(out).flatten(msg)
-        self.assertEqual(out.getvalue(), self.non_latin_bin_msg_as7bit)
+        self.assertEqual(out.getvalue(), self.non_latin_bin_msg_as7bit_wrapped)
 
     def test_bytes_generator_with_unix_from(self):
         # The unixfrom contains a current date, so we can't check it
@@ -2982,6 +2992,12 @@
         self.assertEqual(lines[0].split()[0], b'From')
         self.assertEqual(b'\n'.join(lines[1:]), self.non_latin_bin_msg)
 
+    non_latin_bin_msg_as7bit = non_latin_bin_msg_as7bit_wrapped.split('\n')
+    non_latin_bin_msg_as7bit[2:4] = [
+        'Subject: =?unknown-8bit?q?Maintenant_je_vous_pr=C3=A9sente_mon_coll=C3=A8gue'
+         '=2C_le_pouf_c=C3=A9l=C3=A8bre?=']
+    non_latin_bin_msg_as7bit = '\n'.join(non_latin_bin_msg_as7bit)
+
     def test_message_from_binary_file(self):
         fn = 'test.msg'
         self.addCleanup(unlink, fn)
Index: Lib/email/header.py
===================================================================
--- Lib/email/header.py	(revision 87768)
+++ Lib/email/header.py	(working copy)
@@ -210,6 +210,9 @@
             # from a charset to None/us-ascii, or from None/us-ascii to a
             # charset.  Only do this for the second and subsequent chunks.
             nextcs = charset
+            if nextcs == 'unknown-8bit':
+                original_bytes = string.encode('ascii', 'surrogateescape')
+                string = original_bytes.decode('ascii', 'replace')
             if uchunks:
                 if lastcs not in (None, 'us-ascii'):
                     if nextcs in (None, 'us-ascii'):
@@ -263,7 +266,8 @@
         # Ensure that the bytes we're storing can be decoded to the output
         # character set, otherwise an early error is thrown.
         output_charset = charset.output_codec or 'us-ascii'
-        s.encode(output_charset, errors)
+        if output_charset != 'unknown-8bit':
+            s.encode(output_charset, errors)
         self._chunks.append((s, charset))
 
     def encode(self, splitchars=';, \t', maxlinelen=None, linesep='\n'):
Index: Lib/email/charset.py
===================================================================
--- Lib/email/charset.py	(revision 87768)
+++ Lib/email/charset.py	(working copy)
@@ -153,6 +153,16 @@
 
 
 
+# Convenience function for encoding strings, taking into account
+# that they might be unknown-8bit (ie: have surrogate-escaped bytes)
+def _encode(string, codec):
+    if codec == 'unknown-8bit':
+        return string.encode('ascii', 'surrogateescape')
+    else:
+        return string.encode(codec)
+
+
+
 class Charset:
     """Map character sets to their email properties.
 
@@ -282,8 +292,7 @@
         :return: The encoded string, with RFC 2047 chrome.
         """
         codec = self.output_codec or 'us-ascii'
-        charset = self.get_output_charset()
-        header_bytes = string.encode(codec)
+        header_bytes = _encode(string, codec)
         # 7bit/8bit encodings return the string unchanged (modulo conversions)
         encoder_module = self._get_encoder(header_bytes)
         if encoder_module is None:
@@ -311,7 +320,7 @@
         """
         # See which encoding we should use.
         codec = self.output_codec or 'us-ascii'
-        header_bytes = string.encode(codec)
+        header_bytes = _encode(string, codec)
         encoder_module = self._get_encoder(header_bytes)
         encoder = partial(encoder_module.header_encode, charset=str(self))
         # Calculate the number of characters that the RFC 2047 chrome will
@@ -335,7 +344,7 @@
         for character in string:
             current_line.append(character)
             this_line = EMPTYSTRING.join(current_line)
-            length = encoder_module.header_length(this_line.encode(charset))
+            length = encoder_module.header_length(_encode(this_line, charset))
             if length > maxlen:
                 # This last character doesn't fit so pop it off.
                 current_line.pop()
@@ -345,12 +354,12 @@
                 else:
                     separator = (' ' if lines else '')
                     joined_line = EMPTYSTRING.join(current_line)
-                    header_bytes = joined_line.encode(codec)
+                    header_bytes = _encode(joined_line, codec)
                     lines.append(encoder(header_bytes))
                 current_line = [character]
                 maxlen = next(maxlengths) - extra
         joined_line = EMPTYSTRING.join(current_line)
-        header_bytes = joined_line.encode(codec)
+        header_bytes = _encode(joined_line, codec)
         lines.append(encoder(header_bytes))
         return lines
 
Index: Lib/email/message.py
===================================================================
--- Lib/email/message.py	(revision 87768)
+++ Lib/email/message.py	(working copy)
@@ -16,6 +16,7 @@
 # Intrapackage imports
 from email import utils
 from email import errors
+from email import header
 from email.charset import Charset
 
 SEMISPACE = '; '
@@ -31,16 +32,14 @@
 
 
 # Helper functions
-def _sanitize_surrogates(value):
-    # If the value contains surrogates, re-decode and replace the original
-    # non-ascii bytes with '?'s.  Used to sanitize header values before letting
-    # them escape as strings.
+def _sanitize_header(name, value):
+    # If the header value contains surrogates, return a Header using
+    # the unknown-8bit charset to encode the bytes as encoded words.
     if not isinstance(value, str):
-        # Header object
+        # Assume it is already a header object
         return value
     if _has_surrogates(value):
-        original_bytes = value.encode('ascii', 'surrogateescape')
-        return original_bytes.decode('ascii', 'replace').replace('\ufffd', '?')
+        return header.Header(value, charset='unknown-8bit', header_name=name)
     else:
         return value
 
@@ -398,7 +397,7 @@
         Any fields deleted and re-inserted are always appended to the header
         list.
         """
-        return [_sanitize_surrogates(v) for k, v in self._headers]
+        return [_sanitize_header(k, v) for k, v in self._headers]
 
     def items(self):
         """Get all the message's header fields and values.
@@ -408,7 +407,7 @@
         Any fields deleted and re-inserted are always appended to the header
         list.
         """
-        return [(k, _sanitize_surrogates(v)) for k, v in self._headers]
+        return [(k, _sanitize_header(k, v)) for k, v in self._headers]
 
     def get(self, name, failobj=None):
         """Get a header value.
@@ -419,7 +418,7 @@
         name = name.lower()
         for k, v in self._headers:
             if k.lower() == name:
-                return _sanitize_surrogates(v)
+                return _sanitize_header(k, v)
         return failobj
 
     #
@@ -439,7 +438,7 @@
         name = name.lower()
         for k, v in self._headers:
             if k.lower() == name:
-                values.append(_sanitize_surrogates(v))
+                values.append(_sanitize_header(k, v))
         if not values:
             return failobj
         return values