diff --git a/Doc/library/re.rst b/Doc/library/re.rst
index 2237f07..4fb4016 100644
--- a/Doc/library/re.rst
+++ b/Doc/library/re.rst
@@ -540,7 +540,7 @@
       instead.
 
 
-.. function:: split(pattern, string[, maxsplit=0])
+.. function:: split(pattern, string[, maxsplit=0, flags=0])
 
    Split *string* by the occurrences of *pattern*.  If capturing parentheses are
    used in *pattern*, then the text of all groups in the pattern are also returned
@@ -555,6 +555,8 @@
       ['Words', ', ', 'words', ', ', 'words', '.', '']
       >>> re.split('\W+', 'Words, words, words.', 1)
       ['Words', 'words, words.']
+      >>> re.split('[a-f]+', '0a3B9', flags=re.IGNORECASE)
+      ['0', '3', '9']
 
    If there are capturing groups in the separator and it matches at the start of
    the string, the result will start with an empty string.  The same holds for
@@ -575,6 +577,9 @@
       >>> re.split("(?m)^$", "foo\n\nbar\n")
       ['foo\n\nbar\n']
 
+   .. versionchanged:: 2.7,3.1
+      Added the optional flags argument.
+
 
 .. function:: findall(pattern, string[, flags])
 
@@ -605,7 +610,7 @@
       Added the optional flags argument.
 
 
-.. function:: sub(pattern, repl, string[, count])
+.. function:: sub(pattern, repl, string[, count, flags])
 
    Return the string obtained by replacing the leftmost non-overlapping occurrences
    of *pattern* in *string* by the replacement *repl*.  If the pattern isn't found,
@@ -630,6 +635,8 @@
       ...     else: return '-'
       >>> re.sub('-{1,2}', dashrepl, 'pro----gram-files')
       'pro--gram files'
+      >>> re.sub(r'\sAND\s', ' & ', 'Baked Beans And Spam', flags=re.IGNORECASE)
+      'Baked Beans & Spam'
 
    The pattern may be a string or an RE object; if you need to specify regular
    expression flags, you must use a RE object, or use embedded modifiers in a
@@ -650,12 +657,18 @@
    character ``'0'``.  The backreference ``\g<0>`` substitutes in the entire
    substring matched by the RE.
 
+   .. versionchanged:: 2.7,3.1
+      Added the optional flags argument.
 
-.. function:: subn(pattern, repl, string[, count])
+
+.. function:: subn(pattern, repl, string[, count, flags])
 
    Perform the same operation as :func:`sub`, but return a tuple ``(new_string,
    number_of_subs_made)``.
 
+   .. versionchanged:: 2.7,3.1
+      Added the optional flags argument.
+
 
 .. function:: escape(string)
 
diff --git a/Lib/re.py b/Lib/re.py
index 2cf7132..955b6b5 100644
--- a/Lib/re.py
+++ b/Lib/re.py
@@ -141,16 +141,16 @@
     a match object, or None if no match was found."""
     return _compile(pattern, flags).search(string)
 
-def sub(pattern, repl, string, count=0):
+def sub(pattern, repl, string, count=0, flags=0):
     """Return the string obtained by replacing the leftmost
     non-overlapping occurrences of the pattern in string by the
     replacement repl.  repl can be either a string or a callable;
     if a string, backslash escapes in it are processed.  If it is
     a callable, it's passed the match object and must return
     a replacement string to be used."""
-    return _compile(pattern, 0).sub(repl, string, count)
+    return _compile(pattern, flags).sub(repl, string, count)
 
-def subn(pattern, repl, string, count=0):
+def subn(pattern, repl, string, count=0, flags=0):
     """Return a 2-tuple containing (new_string, number).
     new_string is the string obtained by replacing the leftmost
     non-overlapping occurrences of the pattern in the source
@@ -159,12 +159,12 @@
     callable; if a string, backslash escapes in it are processed.
     If it is a callable, it's passed the match object and must
     return a replacement string to be used."""
-    return _compile(pattern, 0).subn(repl, string, count)
+    return _compile(pattern, flags).subn(repl, string, count)
 
-def split(pattern, string, maxsplit=0):
+def split(pattern, string, maxsplit=0, flags=0):
     """Split the source string by the occurrences of the pattern,
     returning a list containing the resulting substrings."""
-    return _compile(pattern, 0).split(string, maxsplit)
+    return _compile(pattern, flags).split(string, maxsplit)
 
 def findall(pattern, string, flags=0):
     """Return a list of all non-overlapping matches in the string.
diff --git a/Misc/NEWS b/Misc/NEWS
index 49a3885..a9a249a 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -163,6 +163,8 @@
 
 - Issue #3582: Use native TLS functions on Windows
 
+- The re.sub(), re.subn() and re.split() functions now accept a flags parameter.
+
 Library
 -------