diff -rupN Python-2.7.13/configure.ac Python-2.7.13-new/configure.ac
--- Python-2.7.13/configure.ac	2017-01-21 01:46:09.733573102 +0100
+++ Python-2.7.13-new/configure.ac	2017-01-21 01:46:09.735573081 +0100
@@ -2653,14 +2653,32 @@ AC_ARG_WITH(system_ffi,
             [],
             [with_system_ffi="no"])
 
-if test "$with_system_ffi" = "yes" && test -n "$PKG_CONFIG"; then
-    LIBFFI_INCLUDEDIR="`"$PKG_CONFIG" libffi --cflags-only-I 2>/dev/null | sed -e 's/^-I//;s/ *$//'`"
+if test "$with_system_ffi" = "yes"; then
+    LIBFFI_INCLUDEDIR="$LIBFFI_INCLUDEDIR"
+fi
+AC_MSG_RESULT($with_system_ffi)
+
+ac_previous_cppflags=$CPPFLAGS
+CPPFLAGS="-I$LIBFFI_INCLUDEDIR"
+ac_previous_ldflags=$LDFLAGS
+# check for ffi.h
+AC_CHECK_HEADER(ffi.h, [
+  AC_DEFINE(WITH_SYSTEM_LIBFFI, 1,
+  [Define if we have external libffi.])
+  ffi_h="yes"
+],
+ffi_h="no"
+)
+if test "$ffi_h" = "yes"; then
+    LIBFFI_INCLUDEDIR="$LIBFFI_INCLUDEDIR"
 else
     LIBFFI_INCLUDEDIR=""
 fi
+CPPFLAGS=$ac_previous_cppflags
+LDFLAGS=$ac_previous_ldflags
 AC_SUBST(LIBFFI_INCLUDEDIR)
 
-AC_MSG_RESULT($with_system_ffi)
+
 
 # Check for --with-tcltk-includes=path and --with-tcltk-libs=path
 AC_SUBST(TCLTK_INCLUDES)
diff -rupN Python-2.7.13/Lib/ctypes/test/test_as_parameter.py Python-2.7.13-new/Lib/ctypes/test/test_as_parameter.py
--- Python-2.7.13/Lib/ctypes/test/test_as_parameter.py	2016-12-17 21:05:05.000000000 +0100
+++ Python-2.7.13-new/Lib/ctypes/test/test_as_parameter.py	2017-01-21 01:46:09.735573081 +0100
@@ -2,6 +2,7 @@ import unittest
 from ctypes import *
 from ctypes.test import need_symbol
 import _ctypes_test
+import sys
 
 dll = CDLL(_ctypes_test.__file__)
 
@@ -169,6 +170,10 @@ class BasicWrapTestCase(unittest.TestCas
         s2h = dll.ret_2h_func(self.wrap(inp))
         self.assertEqual((s2h.x, s2h.y), (99*2, 88*3))
 
+    # This is known cdecl incompatibility between GCC
+    # and MSVC. It is addressed in GCC issue #36834.
+    # Python libffi detect it and complain.
+    @unittest.skipIf(sys.platform == "win32" and sys.version.find("GCC") >= 0, 'XFAIL GCC(mingw)')
     def test_struct_return_8H(self):
         class S8I(Structure):
             _fields_ = [("a", c_int),
diff -rupN Python-2.7.13/Lib/ctypes/test/test_functions.py Python-2.7.13-new/Lib/ctypes/test/test_functions.py
--- Python-2.7.13/Lib/ctypes/test/test_functions.py	2016-12-17 21:05:05.000000000 +0100
+++ Python-2.7.13-new/Lib/ctypes/test/test_functions.py	2017-01-21 01:46:09.735573081 +0100
@@ -352,6 +352,10 @@ class FunctionTestCase(unittest.TestCase
         s2h = windll.s_ret_2h_func(S2H(99, 88))
         self.assertEqual((s2h.x, s2h.y), (99*2, 88*3))
 
+    # This is known cdecl incompatibility between GCC
+    # and MSVC. It is addressed in GCC issue #36834.
+    # Python libffi detect it and complain.
+    @unittest.skipIf(sys.platform == "win32" and sys.version.find("GCC") >= 0, 'XFAIL GCC(mingw)')
     def test_struct_return_8H(self):
         class S8I(Structure):
             _fields_ = [("a", c_int),
diff -rupN Python-2.7.13/Modules/_ctypes/libffi/fficonfig.py.in Python-2.7.13-new/Modules/_ctypes/libffi/fficonfig.py.in
--- Python-2.7.13/Modules/_ctypes/libffi/fficonfig.py.in	2016-12-17 21:05:07.000000000 +0100
+++ Python-2.7.13-new/Modules/_ctypes/libffi/fficonfig.py.in	2017-01-21 01:46:09.735573081 +0100
@@ -23,6 +23,7 @@ ffi_platforms = {
     'FRV': ['src/frv/eabi.S', 'src/frv/ffi.c'],
     'S390': ['src/s390/sysv.S', 'src/s390/ffi.c'],
     'X86_64': ['src/x86/ffi64.c', 'src/x86/unix64.S', 'src/x86/ffi.c', 'src/x86/sysv.S'],
+    'X86_WIN64': ['src/x86/ffi.c', 'src/x86/win64.S'],
     'SH': ['src/sh/sysv.S', 'src/sh/ffi.c'],
     'SH64': ['src/sh64/sysv.S', 'src/sh64/ffi.c'],
     'PA': ['src/pa/linux.S', 'src/pa/ffi.c'],
@@ -30,6 +31,9 @@ ffi_platforms = {
     'PA_HPUX': ['src/pa/hpux32.S', 'src/pa/ffi.c'],
 }
 
+ffi_target = '@TARGET@'
+if ffi_target not in ['X86_WIN32', 'X86_WIN64']:
+    ffi_sources += 'src/dlmalloc.c'
 ffi_sources += ffi_platforms['@TARGET@']
 
 ffi_cflags = '@CFLAGS@'
diff -rupN Python-2.7.13/pyconfig.h.in Python-2.7.13-new/pyconfig.h.in
--- Python-2.7.13/pyconfig.h.in	2017-01-21 01:46:07.862593078 +0100
+++ Python-2.7.13-new/pyconfig.h.in	2017-01-21 01:46:09.735573081 +0100
@@ -1136,6 +1136,9 @@
 /* Define if you want to compile in Python-specific mallocs */
 #undef WITH_PYMALLOC
 
+/* Define if we have external libffi. */
+#undef WITH_SYSTEM_LIBFFI
+
 /* Define if you want to compile in rudimentary thread support */
 #undef WITH_THREAD
 
diff -rupN Python-2.7.13/setup.py Python-2.7.13-new/setup.py
--- Python-2.7.13/setup.py	2017-01-21 01:46:08.712584003 +0100
+++ Python-2.7.13-new/setup.py	2017-01-21 01:46:09.736573070 +0100
@@ -2074,6 +2074,11 @@ class PyBuildExt(build_ext):
         return True
 
     def configure_ctypes(self, ext):
+        if host_platform in ['mingw', 'win32']:
+            ext.libraries.extend(['ole32', 'oleaut32', 'uuid'])
+            #AdditionalOptions="/EXPORT:DllGetClassObject,PRIVATE /EXPORT:DllCanUnloadNow,PRIVATE"
+            ext.export_symbols.extend(['DllGetClassObject PRIVATE',
+                                       'DllCanUnloadNow PRIVATE'])
         if not self.use_system_libffi:
             if host_platform == 'darwin':
                 return self.configure_ctypes_darwin(ext)
@@ -2098,6 +2103,10 @@ class PyBuildExt(build_ext):
                 if not self.verbose:
                     config_args.append("-q")
 
+                if host_platform in ['mingw', 'win32']:
+                    table = str.maketrans('\\', '/')
+                    ffi_builddir = ffi_builddir.translate(table)
+                    ffi_srcdir = ffi_srcdir.translate(table)
                 # Pass empty CFLAGS because we'll just append the resulting
                 # CFLAGS to Python's; -g or -O2 is to be avoided.
                 cmd = "cd %s && env CFLAGS='' '%s/configure' %s" \