diff -r 0ddba0abab49 Doc/library/http.server.rst
--- a/Doc/library/http.server.rst	Thu Jun 02 10:13:47 2016 +0000
+++ b/Doc/library/http.server.rst	Sat Jun 04 19:12:07 2016 -0700
@@ -191,7 +191,9 @@
       a complete set of headers, as the response body.  The :attr:`responses`
       attribute holds the default values for *message* and *explain* that
       will be used if no value is provided; for unknown codes the default value
-      for both is the string ``???``.
+      for both is the string ``???``. The body will be empty if the method is
+      HEAD or the response code is one of the following: ``1xx``,
+      ``204 No Content``, ``205 Reset Content``, ``304 Not Modified``.
 
       .. versionchanged:: 3.4
          The error response includes a Content-Length header.
diff -r 0ddba0abab49 Lib/http/server.py
--- a/Lib/http/server.py	Thu Jun 02 10:13:47 2016 +0000
+++ b/Lib/http/server.py	Sat Jun 04 19:12:07 2016 -0700
@@ -454,15 +454,22 @@
         })
         body = content.encode('UTF-8', 'replace')
         self.send_response(code, message)
+
+        send_body = (self.command != 'HEAD' and
+                     code >= 200 and
+                     code not in (HTTPStatus.NO_CONTENT,
+                                  HTTPStatus.RESET_CONTENT,
+                                  HTTPStatus.NOT_MODIFIED))
         self.send_header("Content-Type", self.error_content_type)
         self.send_header('Connection', 'close')
-        self.send_header('Content-Length', int(len(body)))
+        if self.command == 'HEAD' or send_body:
+            # Content-Length will not be sent for cases mentioned in below RFCs.
+            #  - RFC7230: 3.3.2. 1xx, 204(No Content), 304(Not Modified)
+            #  - RFC7231: 6.3.6. 205(Reset Content)
+            self.send_header('Content-Length', int(len(body)))
         self.end_headers()
 
-        if (self.command != 'HEAD' and
-                code >= 200 and
-                code not in (
-                    HTTPStatus.NO_CONTENT, HTTPStatus.NOT_MODIFIED)):
+        if send_body:
             self.wfile.write(body)
 
     def send_response(self, code, message=None):
diff -r 0ddba0abab49 Lib/test/test_httpservers.py
--- a/Lib/test/test_httpservers.py	Thu Jun 02 10:13:47 2016 +0000
+++ b/Lib/test/test_httpservers.py	Sat Jun 04 19:12:07 2016 -0700
@@ -116,6 +116,24 @@
             body = self.headers['x-special-incoming'].encode('utf-8')
             self.wfile.write(body)
 
+        def do_NOCONTENT_VIA_SEND_ERROR(self):
+            self.send_error(HTTPStatus.NO_CONTENT)
+
+        def do_RESETCONTENT_VIA_SEND_ERROR(self):
+            self.send_error(HTTPStatus.RESET_CONTENT)
+
+        def do_NOTMODIFIED_VIA_SEND_ERROR(self):
+            self.send_error(HTTPStatus.NOT_MODIFIED)
+
+        def do_SWITCHING_PROTOCOLS_VIA_SEND_ERROR(self):
+            self.send_error(HTTPStatus.SWITCHING_PROTOCOLS)
+
+        def do_PROCESSING_VIA_SEND_ERROR(self):
+            self.send_error(HTTPStatus.PROCESSING)
+
+        def do_HEAD(self):
+            self.send_error(HTTPStatus.OK)
+
     def setUp(self):
         BaseTestCase.setUp(self)
         self.con = http.client.HTTPConnection(self.HOST, self.PORT)
@@ -237,6 +255,63 @@
         data = res.read()
         self.assertEqual(int(res.getheader('Content-Length')), len(data))
 
+    def test_no_content_via_send_error(self):
+        self.con.request('NOCONTENT_VIA_SEND_ERROR', '/')
+        res = self.con.getresponse()
+        self.assertEqual(HTTPStatus.NO_CONTENT, res.status)
+        self.assertEqual(None, res.getheader('Content-Length'))
+
+        data = res.read()
+        self.assertEqual(b'', data)
+
+    def test_reset_content_via_send_error(self):
+        self.con.request('RESETCONTENT_VIA_SEND_ERROR', '/')
+        res = self.con.getresponse()
+        self.assertEqual(HTTPStatus.RESET_CONTENT, res.status)
+        self.assertEqual(None, res.getheader('Content-Length'))
+
+        data = res.read()
+        self.assertEqual(b'', data)
+
+    def test_not_modified_via_send_error(self):
+        self.con.request('NOTMODIFIED_VIA_SEND_ERROR', '/')
+        res = self.con.getresponse()
+        self.assertEqual(HTTPStatus.NOT_MODIFIED, res.status)
+        self.assertEqual(None, res.getheader('Content-Length'))
+        self.assertEqual(None, res.getheader('Transfer-Encoding'))
+
+        data = res.read()
+        self.assertEqual(b'', data)
+
+    def test_switching_protocols_via_send_error(self):
+        self.con.request('SWITCHING_PROTOCOLS_VIA_SEND_ERROR', '/')
+        res = self.con.getresponse()
+        self.assertEqual(HTTPStatus.SWITCHING_PROTOCOLS, res.status)
+        self.assertEqual(None, res.getheader('Content-Length'))
+        self.assertEqual(None, res.getheader('Transfer-Encoding'))
+
+        data = res.read()
+        self.assertEqual(b'', data)
+
+    def test_processing_via_send_error(self):
+        self.con.request('PROCESSING_VIA_SEND_ERROR', '/')
+        res = self.con.getresponse()
+        self.assertEqual(HTTPStatus.PROCESSING, res.status)
+        self.assertEqual(None, res.getheader('Content-Length'))
+        self.assertEqual(None, res.getheader('Transfer-Encoding'))
+
+        data = res.read()
+        self.assertEqual(b'', data)
+
+    def test_head_via_send_error(self):
+        self.con.request('HEAD', '/')
+        res = self.con.getresponse()
+        self.assertEqual(HTTPStatus.OK, res.status)
+        self.assertTrue(int(res.getheader('Content-Length')) > 0)
+
+        data = res.read()
+        self.assertEqual(b'', data)
+
 
 class RequestHandlerLoggingTestCase(BaseTestCase):
     class request_handler(BaseHTTPRequestHandler):