diff -r e28221e52d24 Lib/http/client.py
--- a/Lib/http/client.py	Thu Apr 02 16:25:01 2015 +0200
+++ b/Lib/http/client.py	Thu Apr 02 08:13:20 2015 -0700
@@ -784,9 +784,10 @@
         self.debuglevel = level
 
     def _tunnel(self):
-        connect_str = "CONNECT %s:%d HTTP/1.0\r\n" % (self._tunnel_host,
-            self._tunnel_port)
-        connect_bytes = connect_str.encode("ascii")
+        connect_bytes = b'CONNECT %s:%d %s\r\n' % (
+            self._tunnel_host.encode('idna'),
+            self._tunnel_port,
+            self._http_vsn_str.encode('ascii'))
         self.send(connect_bytes)
         for header, value in self._tunnel_headers.items():
             header_str = "%s: %s\r\n" % (header, value)
diff -r e28221e52d24 Lib/test/test_httplib.py
--- a/Lib/test/test_httplib.py	Thu Apr 02 16:25:01 2015 +0200
+++ b/Lib/test/test_httplib.py	Thu Apr 02 08:13:20 2015 -0700
@@ -1488,6 +1488,16 @@
         # This test should be removed when CONNECT gets the HTTP/1.1 blessing
         self.assertNotIn(b'Host: proxy.com', self.conn.sock.data)
 
+    def test_connect_with_tunnel_idna(self):
+        dest = '\u03b4\u03c0\u03b8.gr'
+        expected = 'CONNECT %s:%d HTTP/1.1\r\n'.encode('ascii') % (
+            dest.encode('idna'), client.HTTP_PORT)
+        self.conn.set_tunnel(dest)
+        self.conn.request('HEAD', '/', '')
+        self.assertEqual(self.conn.sock.host, self.host)
+        self.assertEqual(self.conn.sock.port, client.HTTP_PORT)
+        self.assertIn(expected, self.conn.sock.data)
+
     def test_connect_put_request(self):
         self.conn.set_tunnel('destination.com')
         self.conn.request('PUT', '/', '')
diff -r e28221e52d24 Misc/NEWS
--- a/Misc/NEWS	Thu Apr 02 16:25:01 2015 +0200
+++ b/Misc/NEWS	Thu Apr 02 08:13:20 2015 -0700
@@ -50,6 +50,10 @@
   only calls fstat() once. Before fstat() was called twice, which was not
   necessary.
 
+- Issue #22708: HTTPConnection now uses HTTP/1.1 to establish persistent
+  connections through proxy servers with CONNECT. Destination hosts are now
+  also IDNA-encoded.
+
 Build
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