diff -dur -x '*~' -x '*.orig' Python-3.5.0.orig/Lib/distutils/command/install.py Python-3.5.0/Lib/distutils/command/install.py
--- Python-3.5.0.orig/Lib/distutils/command/install.py	2015-11-25 17:54:32.000000000 +0100
+++ Python-3.5.0/Lib/distutils/command/install.py	2015-11-25 18:06:33.876268151 +0100
@@ -9,6 +9,7 @@
 from distutils.core import Command
 from distutils.debug import DEBUG
 from distutils.sysconfig import get_config_vars
+from distutils.sysconfig import PREFIX, EXEC_PREFIX
 from distutils.errors import DistutilsPlatformError
 from distutils.file_util import write_file
 from distutils.util import convert_path, subst_vars, change_root
@@ -418,8 +419,8 @@
                     raise DistutilsOptionError(
                           "must not supply exec-prefix without prefix")
 
-                self.prefix = os.path.normpath(sys.prefix)
-                self.exec_prefix = os.path.normpath(sys.exec_prefix)
+                self.prefix = PREFIX
+                self.exec_prefix = EXEC_PREFIX
 
             else:
                 if self.exec_prefix is None:
diff -dur -x '*~' -x '*.orig' Python-3.5.0.orig/Lib/distutils/sysconfig.py Python-3.5.0/Lib/distutils/sysconfig.py
--- Python-3.5.0.orig/Lib/distutils/sysconfig.py	2015-11-25 17:54:32.000000000 +0100
+++ Python-3.5.0/Lib/distutils/sysconfig.py	2015-11-25 18:03:39.338573134 +0100
@@ -17,8 +17,12 @@
 from .errors import DistutilsPlatformError
 
 # These are needed in a couple of spots, so just compute them once.
 PREFIX = os.path.normpath(sys.prefix)
 EXEC_PREFIX = os.path.normpath(sys.exec_prefix)
+if PREFIX == "/usr":
+    PREFIX = "/usr/local"
+if EXEC_PREFIX == "/usr":
+    EXEC_PREFIX = "/usr/local"
 BASE_PREFIX = os.path.normpath(sys.base_prefix)
 BASE_EXEC_PREFIX = os.path.normpath(sys.base_exec_prefix)
 
diff -dur -x '*~' -x '*.orig' Python-3.5.0.orig/Lib/site.py Python-3.5.0/Lib/site.py
--- Python-3.5.0.orig/Lib/site.py	2015-11-25 17:54:32.000000000 +0100
+++ Python-3.5.0/Lib/site.py	2015-11-25 17:56:39.979513073 +0100
@@ -74,7 +74,7 @@
 import _sitebuiltins
 
 # Prefixes for site-packages; add additional prefixes like /usr/local here
-PREFIXES = [sys.prefix, sys.exec_prefix]
+PREFIXES = ["/usr/local", sys.prefix, sys.exec_prefix]
 # Enable per user site-packages directory
 # set it to False to disable the feature or True to force the feature
 ENABLE_USER_SITE = None