Index: b/Lib/distutils/sysconfig.py
===================================================================
--- a/Lib/distutils/sysconfig.py
+++ b/Lib/distutils/sysconfig.py
@@ -423,40 +423,11 @@
 _config_vars = None
 
 def _init_posix():
-    """Initialize the module as appropriate for POSIX systems."""
-    g = {}
-    # load the installed Makefile:
-    try:
-        filename = get_makefile_filename()
-        parse_makefile(filename, g)
-    except OSError as msg:
-        my_msg = "invalid Python installation: unable to open %s" % filename
-        if hasattr(msg, "strerror"):
-            my_msg = my_msg + " (%s)" % msg.strerror
-
-        raise DistutilsPlatformError(my_msg)
-
-    # load the installed pyconfig.h:
-    try:
-        filename = get_config_h_filename()
-        with open(filename) as file:
-            parse_config_h(file, g)
-    except OSError as msg:
-        my_msg = "invalid Python installation: unable to open %s" % filename
-        if hasattr(msg, "strerror"):
-            my_msg = my_msg + " (%s)" % msg.strerror
-
-        raise DistutilsPlatformError(my_msg)
-
-    # On AIX, there are wrong paths to the linker scripts in the Makefile
-    # -- these paths are relative to the Python source, but when installed
-    # the scripts are in another directory.
-    if python_build:
-        g['LDSHARED'] = g['BLDSHARED']
-
+    # _sysconfigdata is generated at build time, see the sysconfig module
+    from _sysconfigdata import build_time_vars
     global _config_vars
-    _config_vars = g
-
+    _config_vars = {}
+    _config_vars.update(build_time_vars)
 
 def _init_nt():
     """Initialize the module as appropriate for NT"""
