diff -r c829ad672920 Doc/library/shutil.rst
--- a/Doc/library/shutil.rst	Mon Mar 03 20:06:37 2014 -0800
+++ b/Doc/library/shutil.rst	Mon Mar 03 21:18:13 2014 -0800
@@ -191,14 +191,13 @@
    match one of the glob-style *patterns* provided.  See the example below.
 
 
-.. function:: copytree(src, dst, symlinks=False, ignore=None, copy_function=copy2, ignore_dangling_symlinks=False)
+.. function:: copytree(src, dst, symlinks=False, ignore=None, copy_function=copy2, ignore_dangling_symlinks=False, exist_ok=False)
 
    Recursively copy an entire directory tree rooted at *src*, returning the
    destination directory.  The destination
-   directory, named by *dst*, must not already exist; it will be created as
-   well as missing parent directories.  Permissions and times of directories
-   are copied with :func:`copystat`, individual files are copied using
-   :func:`shutil.copy2`.
+   directory will be created as well as missing parent directories.  Permissions
+   and times of directories are copied with :func:`copystat`, individual files
+   are copied using :func:`shutil.copy2`.
 
    If *symlinks* is true, symbolic links in the source tree are represented as
    symbolic links in the new tree and the metadata of the original links will
@@ -229,6 +228,12 @@
    as arguments. By default, :func:`shutil.copy2` is used, but any function
    that supports the same signature (like :func:`shutil.copy`) can be used.
 
+   If *exist_ok* is ``False`` (the default), an :exc:`OSError` is raised if
+   the target directory already exists.  If *exist_ok* is ``True`` an
+   :exc:`OSError` is still raised if the umask-masked *mode* is different from
+   the existing mode, on systems where the mode is used.  :exc:`OSError` will
+   also be raised if the directory creation fails.
+
    .. versionchanged:: 3.3
       Copy metadata when *symlinks* is false.
       Now returns *dst*.
diff -r c829ad672920 Lib/shutil.py
--- a/Lib/shutil.py	Mon Mar 03 20:06:37 2014 -0800
+++ b/Lib/shutil.py	Mon Mar 03 21:18:13 2014 -0800
@@ -258,7 +258,7 @@
     return _ignore_patterns
 
 def copytree(src, dst, symlinks=False, ignore=None, copy_function=copy2,
-             ignore_dangling_symlinks=False):
+             ignore_dangling_symlinks=False, exist_ok=False):
     """Recursively copy a directory tree.
 
     The destination directory must not already exist.
@@ -299,7 +299,7 @@
     else:
         ignored_names = set()
 
-    os.makedirs(dst)
+    os.makedirs(dst, exist_ok=exist_ok)
     errors = []
     for name in names:
         if name in ignored_names: