diff -r 0d4e0a736688 Doc/using/cmdline.rst
--- a/Doc/using/cmdline.rst	Tue Jan 10 11:27:07 2017 +0800
+++ b/Doc/using/cmdline.rst	Wed Jan 11 13:01:44 2017 -0800
@@ -24,7 +24,7 @@
 
 When invoking Python, you may specify any of these options::
 
-    python [-BdEiOQsRStuUvVWxX3?] [-c command | -m module-name | script | - ] [args]
+    python [-bBdEiOQsRStuUvVWxX3?] [-c command | -m module-name | script | - ] [args]
 
 The most common use case is, of course, a simple invocation of a script::
 
@@ -191,6 +191,14 @@
 Miscellaneous options
 ~~~~~~~~~~~~~~~~~~~~~
 
+.. cmdoption:: -b
+
+   Issue a warning when comparing :class:`bytes` with :class:`bytearray`.
+   Issue an error when the option is given twice (:option:`!-bb`).
+
+   .. versionchanged:: 3.5
+      Affects comparisons of :class:`bytes` with :class:`int`.
+
 .. cmdoption:: -B
 
    If given, Python won't try to write ``.pyc`` or ``.pyo`` files on the
diff -r 0d4e0a736688 Modules/main.c
--- a/Modules/main.c	Tue Jan 10 11:27:07 2017 +0800
+++ b/Modules/main.c	Wed Jan 11 13:01:44 2017 -0800
@@ -62,6 +62,8 @@
 /* Long usage message, split into parts < 512 bytes */
 static char *usage_1 = "\
 Options and arguments (and corresponding environment variables):\n\
+-b     : issue warnings about comparing bytearray with unicode\n\
+         (-bb: issue errors)\n\
 -B     : don't write .py[co] files on import; also PYTHONDONTWRITEBYTECODE=x\n\
 -c cmd : program passed in as string (terminates option list)\n\
 -d     : debug output from parser; also PYTHONDEBUG=x\n\