diff --git a/.gitignore b/.gitignore
index e697112..e2f217b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,5 +21,6 @@ __pycache__
 .DS_Store
 \#*#
 .#*
+.cache
 .coverage
 *.swp
diff --git a/IPython/core/magics/script.py b/IPython/core/magics/script.py
index 2ed3112..c0ad8d3 100644
--- a/IPython/core/magics/script.py
+++ b/IPython/core/magics/script.py
@@ -218,8 +218,8 @@ class ScriptMagics(Magics):
                 print("Error while terminating subprocess (pid=%i): %s" \
                     % (p.pid, e))
             return
-        out = py3compat.bytes_to_str(out)
-        err = py3compat.bytes_to_str(err)
+        out = py3compat.decode(out)
+        err = py3compat.decode(err)
         if args.out:
             self.shell.user_ns[args.out] = out
         else:
diff --git a/IPython/core/tests/test_application.py b/IPython/core/tests/test_application.py
index 34cab5b..45d4272 100644
--- a/IPython/core/tests/test_application.py
+++ b/IPython/core/tests/test_application.py
@@ -10,7 +10,6 @@ from traitlets import Unicode
 
 from IPython.core.application import BaseIPythonApplication
 from IPython.testing import decorators as dec
-from IPython.utils import py3compat
 from IPython.utils.tempdir import TemporaryDirectory
 
 
diff --git a/IPython/core/tests/test_compilerop.py b/IPython/core/tests/test_compilerop.py
index 89c0672..f1f88e4 100644
--- a/IPython/core/tests/test_compilerop.py
+++ b/IPython/core/tests/test_compilerop.py
@@ -22,7 +22,6 @@ import nose.tools as nt
 
 # Our own imports
 from IPython.core import compilerop
-from IPython.utils import py3compat
 
 #-----------------------------------------------------------------------------
 # Test functions
diff --git a/IPython/core/tests/test_completerlib.py b/IPython/core/tests/test_completerlib.py
index 97b561d..6e2a540 100644
--- a/IPython/core/tests/test_completerlib.py
+++ b/IPython/core/tests/test_completerlib.py
@@ -17,7 +17,6 @@ from os.path import join
 import nose.tools as nt
 
 from IPython.core.completerlib import magic_run_completer, module_completion
-from IPython.utils import py3compat
 from IPython.utils.tempdir import TemporaryDirectory
 from IPython.testing.decorators import onlyif_unicode_paths
 
diff --git a/IPython/core/tests/test_history.py b/IPython/core/tests/test_history.py
index b292a64..fcc22f1 100644
--- a/IPython/core/tests/test_history.py
+++ b/IPython/core/tests/test_history.py
@@ -19,7 +19,6 @@ import nose.tools as nt
 from traitlets.config.loader import Config
 from IPython.utils.tempdir import TemporaryDirectory
 from IPython.core.history import HistoryManager, extract_hist_ranges
-from IPython.utils import py3compat
 
 def setUp():
     nt.assert_equal(sys.getdefaultencoding(), "utf-8")
diff --git a/IPython/core/tests/test_interactiveshell.py b/IPython/core/tests/test_interactiveshell.py
index d275f96..8b93405 100644
--- a/IPython/core/tests/test_interactiveshell.py
+++ b/IPython/core/tests/test_interactiveshell.py
@@ -17,7 +17,6 @@ import sys
 import tempfile
 import unittest
 from unittest import mock
-from io import StringIO
 
 from os.path import join
 
@@ -30,7 +29,6 @@ from IPython.testing.decorators import (
 )
 from IPython.testing import tools as tt
 from IPython.utils.process import find_cmd
-from IPython.utils import py3compat
 
 #-----------------------------------------------------------------------------
 # Globals
diff --git a/IPython/core/tests/test_oinspect.py b/IPython/core/tests/test_oinspect.py
index b7c2742..d94bbf1 100644
--- a/IPython/core/tests/test_oinspect.py
+++ b/IPython/core/tests/test_oinspect.py
@@ -19,10 +19,8 @@ from IPython.core.magic import (Magics, magics_class, line_magic,
                                 register_line_cell_magic)
 from decorator import decorator
 from IPython import get_ipython
-from IPython.testing.decorators import skipif
 from IPython.testing.tools import AssertPrints, AssertNotPrints
 from IPython.utils.path import compress_user
-from IPython.utils import py3compat
 
 
 #-----------------------------------------------------------------------------
@@ -40,14 +38,14 @@ ip = get_ipython()
 # defined, if any code is inserted above, the following line will need to be
 # updated.  Do NOT insert any whitespace between the next line and the function
 # definition below.
-THIS_LINE_NUMBER = 43  # Put here the actual number of this line
+THIS_LINE_NUMBER = 41  # Put here the actual number of this line
 
 from unittest import TestCase
 
 class Test(TestCase):
 
     def test_find_source_lines(self):
-        self.assertEqual(oinspect.find_source_lines(Test.test_find_source_lines), 
+        self.assertEqual(oinspect.find_source_lines(Test.test_find_source_lines),
                     THIS_LINE_NUMBER+6)
 
 
diff --git a/IPython/core/tests/test_splitinput.py b/IPython/core/tests/test_splitinput.py
index 170d923..98b4189 100644
--- a/IPython/core/tests/test_splitinput.py
+++ b/IPython/core/tests/test_splitinput.py
@@ -3,7 +3,6 @@ import nose.tools as nt
 
 from IPython.core.splitinput import split_user_input, LineInfo
 from IPython.testing import tools as tt
-from IPython.utils import py3compat
 
 tests = [
     ('x=1', ('', '', 'x', '=1')),
diff --git a/IPython/core/ultratb.py b/IPython/core/ultratb.py
index bce01e9..e1c1cae 100644
--- a/IPython/core/ultratb.py
+++ b/IPython/core/ultratb.py
@@ -1136,35 +1136,32 @@ class VerboseTB(TBTools):
         colorsnormal = colors.Normal  # used a lot
         head = '%s%s%s' % (colors.topline, '-' * min(75, get_terminal_size()[0]), colorsnormal)
         structured_traceback_parts = [head]
-        if py3compat.PY3:
-            chained_exceptions_tb_offset = 0
-            lines_of_context = 3
-            formatted_exceptions = formatted_exception
+        chained_exceptions_tb_offset = 0
+        lines_of_context = 3
+        formatted_exceptions = formatted_exception
+        exception = self.get_parts_of_chained_exception(evalue)
+        if exception:
+            formatted_exceptions += self.prepare_chained_exception_message(evalue.__cause__)
+            etype, evalue, etb = exception
+        else:
+            evalue = None
+        chained_exc_ids = set()
+        while evalue:
+            formatted_exceptions += self.format_exception_as_a_whole(etype, evalue, etb, lines_of_context,
+                                                                     chained_exceptions_tb_offset)
             exception = self.get_parts_of_chained_exception(evalue)
-            if exception:
+
+            if exception and not id(exception[1]) in chained_exc_ids:
+                chained_exc_ids.add(id(exception[1])) # trace exception to avoid infinite 'cause' loop
                 formatted_exceptions += self.prepare_chained_exception_message(evalue.__cause__)
                 etype, evalue, etb = exception
             else:
                 evalue = None
-            chained_exc_ids = set()
-            while evalue:
-                formatted_exceptions += self.format_exception_as_a_whole(etype, evalue, etb, lines_of_context,
-                                                                         chained_exceptions_tb_offset)
-                exception = self.get_parts_of_chained_exception(evalue)
-
-                if exception and not id(exception[1]) in chained_exc_ids:
-                    chained_exc_ids.add(id(exception[1])) # trace exception to avoid infinite 'cause' loop
-                    formatted_exceptions += self.prepare_chained_exception_message(evalue.__cause__)
-                    etype, evalue, etb = exception
-                else:
-                    evalue = None
 
-            # we want to see exceptions in a reversed order:
-            # the first exception should be on top
-            for formatted_exception in reversed(formatted_exceptions):
-                structured_traceback_parts += formatted_exception
-        else:
-            structured_traceback_parts += formatted_exception[0]
+        # we want to see exceptions in a reversed order:
+        # the first exception should be on top
+        for formatted_exception in reversed(formatted_exceptions):
+            structured_traceback_parts += formatted_exception
 
         return structured_traceback_parts
 
diff --git a/IPython/extensions/autoreload.py b/IPython/extensions/autoreload.py
index 207d03a..a248c1d 100644
--- a/IPython/extensions/autoreload.py
+++ b/IPython/extensions/autoreload.py
@@ -116,7 +116,6 @@ import traceback
 import types
 import weakref
 from importlib import import_module
-from IPython.utils.py3compat import PY3
 from imp import reload
 
 from IPython.utils import openpy
diff --git a/IPython/lib/security.py b/IPython/lib/security.py
index 8429c2a..91a2344 100644
--- a/IPython/lib/security.py
+++ b/IPython/lib/security.py
@@ -11,7 +11,7 @@ import random
 
 # Our own
 from IPython.core.error import UsageError
-from IPython.utils.py3compat import cast_bytes, str_to_bytes
+from IPython.utils.py3compat import encode
 
 #-----------------------------------------------------------------------------
 # Globals
@@ -65,7 +65,7 @@ def passwd(passphrase=None, algorithm='sha1'):
 
     h = hashlib.new(algorithm)
     salt = ('%0' + str(salt_len) + 'x') % random.getrandbits(4 * salt_len)
-    h.update(cast_bytes(passphrase, 'utf-8') + str_to_bytes(salt, 'ascii'))
+    h.update(encode(passphrase, 'utf-8') + encode(salt, 'ascii'))
 
     return ':'.join((algorithm, salt, h.hexdigest()))
 
@@ -109,6 +109,6 @@ def passwd_check(hashed_passphrase, passphrase):
     if len(pw_digest) == 0:
         return False
 
-    h.update(cast_bytes(passphrase, 'utf-8') + cast_bytes(salt, 'ascii'))
+    h.update(encode(passphrase, 'utf-8') + encode(salt, 'ascii'))
 
     return h.hexdigest() == pw_digest
diff --git a/IPython/terminal/interactiveshell.py b/IPython/terminal/interactiveshell.py
index a7ca2b2..3ebd087 100644
--- a/IPython/terminal/interactiveshell.py
+++ b/IPython/terminal/interactiveshell.py
@@ -7,7 +7,7 @@ from warnings import warn
 
 from IPython.core.interactiveshell import InteractiveShell, InteractiveShellABC
 from IPython.utils import io
-from IPython.utils.py3compat import input, cast_unicode_py2
+from IPython.utils.py3compat import input
 from IPython.utils.terminal import toggle_set_term_title, set_term_title
 from IPython.utils.process import abbrev_cwd
 from traitlets import (
@@ -233,7 +233,7 @@ class TerminalInteractiveShell(InteractiveShell):
                 prompt_text = "".join(x[1] for x in self.prompts.in_prompt_tokens())
                 prompt_continuation = "".join(x[1] for x in self.prompts.continuation_prompt_tokens())
                 while isp.push_accepts_more():
-                    line = cast_unicode_py2(input(prompt_text))
+                    line = input(prompt_text)
                     isp.push(line)
                     prompt_text = prompt_continuation
                 return isp.source_reset()
diff --git a/IPython/testing/decorators.py b/IPython/testing/decorators.py
index 4dd8a7e..4f13ce5 100644
--- a/IPython/testing/decorators.py
+++ b/IPython/testing/decorators.py
@@ -31,8 +31,9 @@ we've copied verbatim from numpy.
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-import sys
 import os
+import shutil
+import sys
 import tempfile
 import unittest
 import warnings
@@ -48,9 +49,6 @@ from .ipunittest import ipdoctest, ipdocstring
 # numpy.testing.decorators, we expose all of it here.
 from IPython.external.decorators import *
 
-# For onlyif_cmd_exists decorator
-from IPython.utils.py3compat import which
-
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
@@ -360,7 +358,7 @@ def onlyif_cmds_exist(*commands):
     Decorator to skip test when at least one of `commands` is not found.
     """
     for cmd in commands:
-        if not which(cmd):
+        if not shutil.which(cmd):
             return skip("This test runs only if command '{0}' "
                         "is installed".format(cmd))
     return null_deco
@@ -372,7 +370,7 @@ def onlyif_any_cmd_exists(*commands):
     warnings.warn("The function `onlyif_any_cmd_exists` is deprecated since IPython 4.0",
             DeprecationWarning, stacklevel=2)
     for cmd in commands:
-        if which(cmd):
+        if shutil.which(cmd):
             return null_deco
     return skip("This test runs only if one of the commands {0} "
                 "is installed".format(commands))
diff --git a/IPython/testing/globalipapp.py b/IPython/testing/globalipapp.py
index f9b1d3a..bd57adf 100644
--- a/IPython/testing/globalipapp.py
+++ b/IPython/testing/globalipapp.py
@@ -11,13 +11,13 @@ done.
 
 import builtins as builtin_mod
 import sys
+import types
 import warnings
 
 from . import tools
 
 from IPython.core import page
 from IPython.utils import io
-from IPython.utils import py3compat
 from IPython.terminal.interactiveshell import TerminalInteractiveShell
 
 
@@ -104,9 +104,9 @@ def start_ipython():
     # Modify the IPython system call with one that uses getoutput, so that we
     # can capture subcommands and print them to Python's stdout, otherwise the
     # doctest machinery would miss them.
-    shell.system = py3compat.MethodType(xsys, shell)
-    
-    shell._showtraceback = py3compat.MethodType(_showtraceback, shell)
+    shell.system = types.MethodType(xsys, shell)
+
+    shell._showtraceback = types.MethodType(_showtraceback, shell)
 
     # IPython is ready, now clean up some global state...
 
diff --git a/IPython/testing/iptest.py b/IPython/testing/iptest.py
index c9e9d36..1a302b9 100644
--- a/IPython/testing/iptest.py
+++ b/IPython/testing/iptest.py
@@ -34,7 +34,7 @@ from nose.plugins import Plugin
 from nose.util import safe_str
 
 from IPython import version_info
-from IPython.utils.py3compat import bytes_to_str
+from IPython.utils.py3compat import decode
 from IPython.utils.importstring import import_item
 from IPython.testing.plugin.ipdoctest import IPythonDoctest
 from IPython.external.decorators import KnownFailure, knownfailureif
@@ -299,8 +299,8 @@ class StreamCapturer(Thread):
             with self.buffer_lock:
                 self.buffer.write(chunk)
             if self.echo:
-                sys.stdout.write(bytes_to_str(chunk))
-    
+                sys.stdout.write(decode(chunk))
+
         os.close(self.readfd)
         os.close(self.writefd)
 
diff --git a/IPython/testing/iptestcontroller.py b/IPython/testing/iptestcontroller.py
index cbbb91b..ab76f83 100644
--- a/IPython/testing/iptestcontroller.py
+++ b/IPython/testing/iptestcontroller.py
@@ -24,7 +24,7 @@ from .iptest import (
     have, test_group_names as py_test_group_names, test_sections, StreamCapturer,
 )
 from IPython.utils.path import compress_user
-from IPython.utils.py3compat import bytes_to_str
+from IPython.utils.py3compat import decode
 from IPython.utils.sysinfo import get_sys_info
 from IPython.utils.tempdir import TemporaryDirectory
 
@@ -371,7 +371,7 @@ def run_iptestall(options):
                 print(justify('Test group: ' + controller.section, res_string))
                 if res:
                     controller.print_extra_info()
-                    print(bytes_to_str(controller.stdout))
+                    print(decode(controller.stdout))
                     failed.append(controller)
                     if res == -signal.SIGINT:
                         print("Interrupted")
diff --git a/IPython/testing/tools.py b/IPython/testing/tools.py
index 8eca4f9..b4e570b 100644
--- a/IPython/testing/tools.py
+++ b/IPython/testing/tools.py
@@ -33,7 +33,6 @@ from IPython.utils.process import get_output_error_code
 from IPython.utils.text import list_strings
 from IPython.utils.io import temp_pyfile, Tee
 from IPython.utils import py3compat
-from IPython.utils.encoding import DEFAULT_ENCODING
 
 from . import decorators as dec
 from . import skipdoctest
@@ -210,8 +209,8 @@ def ipexec(fname, options=None, commands=()):
         if not isinstance(v, str):
             print(k, v)
     p = Popen(full_cmd, stdout=PIPE, stderr=PIPE, stdin=PIPE, env=env)
-    out, err = p.communicate(input=py3compat.str_to_bytes('\n'.join(commands)) or None)
-    out, err = py3compat.bytes_to_str(out), py3compat.bytes_to_str(err)
+    out, err = p.communicate(input=py3compat.encode('\n'.join(commands)) or None)
+    out, err = py3compat.decode(out), py3compat.decode(err)
     # `import readline` causes 'ESC[?1034h' to be output sometimes,
     # so strip that out before doing comparisons
     if out:
diff --git a/IPython/utils/_process_cli.py b/IPython/utils/_process_cli.py
index a7b7b90..89a31c3 100644
--- a/IPython/utils/_process_cli.py
+++ b/IPython/utils/_process_cli.py
@@ -28,7 +28,7 @@ def _find_cmd(cmd):
     for path in paths:
         filename = os.path.join(path, cmd)
         if System.IO.File.Exists(filename):
-            return py3compat.bytes_to_str(filename)
+            return py3compat.decode(filename)
     raise OSError("command %r not found" % cmd)
 
 def system(cmd):
diff --git a/IPython/utils/_process_common.py b/IPython/utils/_process_common.py
index 204092b..2a647dc 100644
--- a/IPython/utils/_process_common.py
+++ b/IPython/utils/_process_common.py
@@ -130,7 +130,7 @@ def getoutput(cmd):
     out = process_handler(cmd, lambda p: p.communicate()[0], subprocess.STDOUT)
     if out is None:
         return ''
-    return py3compat.bytes_to_str(out)
+    return py3compat.decode(out)
 
 
 def getoutputerror(cmd):
@@ -172,7 +172,7 @@ def get_output_error_code(cmd):
     if out_err is None:
         return '', '', p.returncode
     out, err = out_err
-    return py3compat.bytes_to_str(out), py3compat.bytes_to_str(err), p.returncode
+    return py3compat.decode(out), py3compat.decode(err), p.returncode
 
 def arg_split(s, posix=False, strict=True):
     """Split a command line's arguments in a shell-like manner.
diff --git a/IPython/utils/_process_posix.py b/IPython/utils/_process_posix.py
index 5907e7d..f3f93f7 100644
--- a/IPython/utils/_process_posix.py
+++ b/IPython/utils/_process_posix.py
@@ -36,7 +36,7 @@ def _find_cmd(cmd):
 
     path = sp.Popen(['/usr/bin/env', 'which', cmd],
                     stdout=sp.PIPE, stderr=sp.PIPE).communicate()[0]
-    return py3compat.bytes_to_str(path)
+    return py3compat.decode(path)
 
 
 class ProcessHandler(object):
diff --git a/IPython/utils/_process_win32.py b/IPython/utils/_process_win32.py
index bfad1b5..115d412 100644
--- a/IPython/utils/_process_win32.py
+++ b/IPython/utils/_process_win32.py
@@ -152,7 +152,7 @@ def getoutput(cmd):
 
     if out is None:
         out = b''
-    return py3compat.bytes_to_str(out)
+    return py3compat.decode(out)
 
 try:
     CommandLineToArgvW = ctypes.windll.shell32.CommandLineToArgvW
diff --git a/IPython/utils/_process_win32_controller.py b/IPython/utils/_process_win32_controller.py
index 4fd2e3c..c2e2329 100644
--- a/IPython/utils/_process_win32_controller.py
+++ b/IPython/utils/_process_win32_controller.py
@@ -15,9 +15,6 @@ This file is meant to be used by process.py
 import os, sys, threading
 import ctypes, msvcrt
 
-# local imports
-from . import py3compat
-
 # Win32 API types needed for the API calls
 from ctypes import POINTER
 from ctypes.wintypes import HANDLE, HLOCAL, LPVOID, WORD, DWORD, BOOL, \
diff --git a/IPython/utils/process.py b/IPython/utils/process.py
index 77b2064..489b7c1 100644
--- a/IPython/utils/process.py
+++ b/IPython/utils/process.py
@@ -8,6 +8,7 @@ Utilities for working with external processes.
 
 
 import os
+import shutil
 import sys
 
 if sys.platform == 'win32':
@@ -18,7 +19,6 @@ else:
     from ._process_posix import system, getoutput, arg_split, check_pid
 
 from ._process_common import getoutputerror, get_output_error_code, process_handler
-from . import py3compat
 
 
 class FindCmdError(Exception):
@@ -44,7 +44,7 @@ def find_cmd(cmd):
     cmd : str
         The command line program to look for.
     """
-    path = py3compat.which(cmd)
+    path = shutil.which(cmd)
     if path is None:
         raise FindCmdError('command could not be found: %s' % cmd)
     return path
diff --git a/IPython/utils/py3compat.py b/IPython/utils/py3compat.py
index 88602e5..cda007a 100644
--- a/IPython/utils/py3compat.py
+++ b/IPython/utils/py3compat.py
@@ -143,153 +143,72 @@ def _shutil_which(cmd, mode=os.F_OK | os.X_OK, path=None):
                     return name
     return None
 
-if sys.version_info[0] >= 3:
-    PY3 = True
-    
-    # keep reference to builtin_mod because the kernel overrides that value
-    # to forward requests to a frontend.
-    def input(prompt=''):
-        return builtin_mod.input(prompt)
-    
-    builtin_mod_name = "builtins"
-    import builtins as builtin_mod
-    
-    str_to_unicode = no_code
-    unicode_to_str = no_code
-    str_to_bytes = encode
-    bytes_to_str = decode
-    cast_bytes_py2 = no_code
-    cast_unicode_py2 = no_code
-    buffer_to_bytes_py2 = no_code
-    
-    string_types = (str,)
-    unicode_type = str
-    
-    which = shutil.which
-    
-    def isidentifier(s, dotted=False):
-        if dotted:
-            return all(isidentifier(a) for a in s.split("."))
-        return s.isidentifier()
-
-    xrange = range
-    def iteritems(d): return iter(d.items())
-    def itervalues(d): return iter(d.values())
-    getcwd = os.getcwd
-    
-    MethodType = types.MethodType
-
-    def execfile(fname, glob, loc=None, compiler=None):
-        loc = loc if (loc is not None) else glob
-        with open(fname, 'rb') as f:
-            compiler = compiler or compile
-            exec(compiler(f.read(), fname, 'exec'), glob, loc)
-    
-    # Refactor print statements in doctests.
-    _print_statement_re = re.compile(r"\bprint (?P<expr>.*)$", re.MULTILINE)
-    def _print_statement_sub(match):
-        expr = match.groups('expr')
-        return "print(%s)" % expr
-    
-    @_modify_str_or_docstring
-    def doctest_refactor_print(doc):
-        """Refactor 'print x' statements in a doctest to print(x) style. 2to3
-        unfortunately doesn't pick up on our doctests.
-        
-        Can accept a string or a function, so it can be used as a decorator."""
-        return _print_statement_re.sub(_print_statement_sub, doc)
-    
-    # Abstract u'abc' syntax:
-    @_modify_str_or_docstring
-    def u_format(s):
-        """"{u}'abc'" --> "'abc'" (Python 3)
-        
-        Accepts a string or a function, so it can be used as a decorator."""
-        return s.format(u='')
-    
-    def get_closure(f):
-        """Get a function's closure attribute"""
-        return f.__closure__
-
-else:
-    PY3 = False
-    
-    # keep reference to builtin_mod because the kernel overrides that value
-    # to forward requests to a frontend.
-    def input(prompt=''):
-        return builtin_mod.raw_input(prompt)
-    
-    builtin_mod_name = "__builtin__"
-    import __builtin__ as builtin_mod
-    
-    str_to_unicode = decode
-    unicode_to_str = encode
-    str_to_bytes = no_code
-    bytes_to_str = no_code
-    cast_bytes_py2 = cast_bytes
-    cast_unicode_py2 = cast_unicode
-    buffer_to_bytes_py2 = buffer_to_bytes
-    
-    string_types = (str, unicode)
-    unicode_type = unicode
-    
-    import re
-    _name_re = re.compile(r"[a-zA-Z_][a-zA-Z0-9_]*$")
-    def isidentifier(s, dotted=False):
-        if dotted:
-            return all(isidentifier(a) for a in s.split("."))
-        return bool(_name_re.match(s))
-    
-    xrange = xrange
-    def iteritems(d): return d.iteritems()
-    def itervalues(d): return d.itervalues()
-    getcwd = os.getcwdu
-
-    def MethodType(func, instance):
-        return types.MethodType(func, instance, type(instance))
-    
-    def doctest_refactor_print(func_or_str):
-        return func_or_str
-
-    def get_closure(f):
-        """Get a function's closure attribute"""
-        return f.func_closure
-    
-    which = _shutil_which
-
-    # Abstract u'abc' syntax:
-    @_modify_str_or_docstring
-    def u_format(s):
-        """"{u}'abc'" --> "u'abc'" (Python 2)
-        
-        Accepts a string or a function, so it can be used as a decorator."""
-        return s.format(u='u')
-
-    if sys.platform == 'win32':
-        def execfile(fname, glob=None, loc=None, compiler=None):
-            loc = loc if (loc is not None) else glob
-            scripttext = builtin_mod.open(fname).read()+ '\n'
-            # compile converts unicode filename to str assuming
-            # ascii. Let's do the conversion before calling compile
-            if isinstance(fname, unicode):
-                filename = unicode_to_str(fname)
-            else:
-                filename = fname
-            compiler = compiler or compile
-            exec(compiler(scripttext, filename, 'exec'), glob, loc)
-
-    else:
-        def execfile(fname, glob=None, loc=None, compiler=None):
-            if isinstance(fname, unicode):
-                filename = fname.encode(sys.getfilesystemencoding())
-            else:
-                filename = fname
-            where = [ns for ns in [glob, loc] if ns is not None]
-            if compiler is None:
-                builtin_mod.execfile(filename, *where)
-            else:
-                scripttext = builtin_mod.open(fname).read().rstrip() + '\n'
-                exec(compiler(scripttext, filename, 'exec'), glob, loc)
+PY3 = True
+
+# keep reference to builtin_mod because the kernel overrides that value
+# to forward requests to a frontend.
+def input(prompt=''):
+    return builtin_mod.input(prompt)
+
+builtin_mod_name = "builtins"
+import builtins as builtin_mod
+
+str_to_unicode = no_code
+unicode_to_str = no_code
+str_to_bytes = encode
+bytes_to_str = decode
+cast_bytes_py2 = no_code
+cast_unicode_py2 = no_code
+buffer_to_bytes_py2 = no_code
+
+string_types = (str,)
+unicode_type = str
+
+which = shutil.which
+
+def isidentifier(s, dotted=False):
+    if dotted:
+        return all(isidentifier(a) for a in s.split("."))
+    return s.isidentifier()
+
+xrange = range
+def iteritems(d): return iter(d.items())
+def itervalues(d): return iter(d.values())
+getcwd = os.getcwd
+
+MethodType = types.MethodType
+
+def execfile(fname, glob, loc=None, compiler=None):
+    loc = loc if (loc is not None) else glob
+    with open(fname, 'rb') as f:
+        compiler = compiler or compile
+        exec(compiler(f.read(), fname, 'exec'), glob, loc)
+
+# Refactor print statements in doctests.
+_print_statement_re = re.compile(r"\bprint (?P<expr>.*)$", re.MULTILINE)
+def _print_statement_sub(match):
+    expr = match.groups('expr')
+    return "print(%s)" % expr
+
+@_modify_str_or_docstring
+def doctest_refactor_print(doc):
+    """Refactor 'print x' statements in a doctest to print(x) style. 2to3
+    unfortunately doesn't pick up on our doctests.
+
+    Can accept a string or a function, so it can be used as a decorator."""
+    return _print_statement_re.sub(_print_statement_sub, doc)
+
+# Abstract u'abc' syntax:
+@_modify_str_or_docstring
+def u_format(s):
+    """"{u}'abc'" --> "'abc'" (Python 3)
+
+    Accepts a string or a function, so it can be used as a decorator."""
+    return s.format(u='')
+
+def get_closure(f):
+    """Get a function's closure attribute"""
+    return f.__closure__
 
 
 PY2 = not PY3
diff --git a/IPython/utils/tokenize2.py b/IPython/utils/tokenize2.py
index 9da7f3c..3f653bb 100644
--- a/IPython/utils/tokenize2.py
+++ b/IPython/utils/tokenize2.py
@@ -91,11 +91,7 @@ Expfloat = r'[0-9]+' + Exponent
 Floatnumber = group(Pointfloat, Expfloat)
 Imagnumber = group(r'[0-9]+[jJ]', Floatnumber + r'[jJ]')
 Number = group(Imagnumber, Floatnumber, Intnumber)
-
-if sys.version_info.minor >= 3:
-    StringPrefix = r'(?:[bB][rR]?|[rR][bB]?|[uU])?'
-else:
-    StringPrefix = r'(?:[bB]?[rR]?)?'
+StringPrefix = r'(?:[bB][rR]?|[rR][bB]?|[uU])?'
 
 # Tail end of ' string.
 Single = r"[^'\\]*(?:\\.[^'\\]*)*'"
@@ -165,20 +161,18 @@ for t in ("'", '"',
           "bR'", 'bR"', "BR'", 'BR"' ):
     single_quoted[t] = t
 
-if sys.version_info.minor >= 3:
-    # Python 3.3
-    for _prefix in ['rb', 'rB', 'Rb', 'RB', 'u', 'U']:
-        _t2 = _prefix+'"""'
-        endprogs[_t2] = double3prog
-        triple_quoted[_t2] = _t2
-        _t1 = _prefix + "'''"
-        endprogs[_t1] = single3prog
-        triple_quoted[_t1] = _t1
-        single_quoted[_prefix+'"'] = _prefix+'"'
-        single_quoted[_prefix+"'"] = _prefix+"'"
-    del _prefix, _t2, _t1
-    endprogs['u'] = None
-    endprogs['U'] = None
+for _prefix in ['rb', 'rB', 'Rb', 'RB', 'u', 'U']:
+    _t2 = _prefix+'"""'
+    endprogs[_t2] = double3prog
+    triple_quoted[_t2] = _t2
+    _t1 = _prefix + "'''"
+    endprogs[_t1] = single3prog
+    triple_quoted[_t1] = _t1
+    single_quoted[_prefix+'"'] = _prefix+'"'
+    single_quoted[_prefix+"'"] = _prefix+"'"
+del _prefix, _t2, _t1
+endprogs['u'] = None
+endprogs['U'] = None
 
 del _compile
 
diff --git a/setupbase.py b/setupbase.py
index 0fedf16..23b3c89 100644
--- a/setupbase.py
+++ b/setupbase.py
@@ -40,15 +40,9 @@ def oscmd(s):
     print(">", s)
     os.system(s)
 
-# Py3 compatibility hacks, without assuming IPython itself is installed with
-# the full py3compat machinery.
-
-try:
-    execfile
-except NameError:
-    def execfile(fname, globs, locs=None):
-        locs = locs or globs
-        exec(compile(open(fname).read(), fname, "exec"), globs, locs)
+def execfile(fname, globs, locs=None):
+    locs = locs or globs
+    exec(compile(open(fname).read(), fname, "exec"), globs, locs)
 
 # A little utility we'll need below, since glob() does NOT allow you to do
 # exclusion on multiple endings!
diff --git a/tox.ini b/tox.ini
index 1668ce6..163f8dc 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,7 +10,7 @@
 ; tox -- --all -j  # Runs "iptest --all -j" in every environment
 
 [tox]
-envlist = py{36,35,34,33,27,py}
+envlist = py{36,35,34,33,py}
 skip_missing_interpreters = True
 toxworkdir = /tmp/tox_ipython
 
@@ -19,7 +19,7 @@ toxworkdir = /tmp/tox_ipython
 ; Other IPython/testing dependencies should be in setup.py, not here
 deps =
   pypy: https://bitbucket.org/pypy/numpy/get/master.zip
-  py{36,35,34,33,27}: matplotlib
+  py{36,35,34,33}: matplotlib
   .[test]
 
 ; It's just to avoid loading the IPython package in the current directory