diff --git a/Lib/distutils/command/upload.py b/Lib/distutils/command/upload.py
index 3b4a036718f..f602fbeb686 100644
--- a/Lib/distutils/command/upload.py
+++ b/Lib/distutils/command/upload.py
@@ -12,7 +12,7 @@ import socket
 import platform
 import configparser
 import http.client as httpclient
-import base64
+from base64 import standard_b64encode
 import urllib.parse
 
 # this keeps compatibility for 2.3 and 2.4
@@ -127,7 +127,7 @@ class upload(PyPIRCCommand):
         user_pass = (self.username + ":" + self.password).encode('ascii')
         # The exact encoding of the authentication string is debated.
         # Anyway PyPI only accepts ascii for both username or password.
-        auth = "Basic " + base64.encodebytes(user_pass).strip().decode('ascii')
+        auth = "Basic " + standard_b64encode(user_pass).decode('ascii')
 
         # Build up the MIME payload for the POST data
         boundary = '--------------GHSKFJDLGDS7543FJKLFHRE75642756743254'
diff --git a/Lib/distutils/tests/test_upload.py b/Lib/distutils/tests/test_upload.py
index 828f20c5399..35e970051e9 100644
--- a/Lib/distutils/tests/test_upload.py
+++ b/Lib/distutils/tests/test_upload.py
@@ -10,6 +10,25 @@ from distutils.core import Distribution
 from distutils.tests import support
 from distutils.tests.test_config import PYPIRC, PyPIRCCommandTestCase
 
+PYPIRC_LONG_PASSWORD = """\
+[distutils]
+
+index-servers =
+    server1
+    server2
+
+[server1]
+username:me
+password:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+
+[server2]
+username:meagain
+password: secret
+realm:acme
+repository:http://another.pypi/
+"""
+
+
 PYPIRC_NOPASSWORD = """\
 [distutils]
 
@@ -96,7 +115,7 @@ class uploadTestCase(PyPIRCCommandTestCase):
         self.write_file(path)
         command, pyversion, filename = 'xxx', '2.6', path
         dist_files = [(command, pyversion, filename)]
-        self.write_file(self.rc, PYPIRC)
+        self.write_file(self.rc, PYPIRC_LONG_PASSWORD)
 
         # lets run it
         pkg_dir, dist = self.create_dist(dist_files=dist_files)
@@ -108,6 +127,7 @@ class uploadTestCase(PyPIRCCommandTestCase):
         headers = dict(self.conn.headers)
         self.assertEquals(headers['Content-length'], '2087')
         self.assertTrue(headers['Content-type'].startswith('multipart/form-data'))
+        self.assertFalse('\n' in headers['Authorization'])
 
         self.assertEquals(self.conn.requests, [('POST', '/pypi')])
         self.assert_((b'xxx') in self.conn.body)
diff --git a/Misc/NEWS b/Misc/NEWS
index dc33c569d8e..05bace37026 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -58,6 +58,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #7552: Removed line feed in the base64 Authorization header in
+  the Distutils upload command to avoid an error when PyPI reads it.
+  This occurs on long passwords. Initial patch by JP St. Pierre.
+
 - Issue #7231: urllib2 cannot handle https with proxy requiring auth.  Patch by
   Tatsuhiro Tsujikawa.