diff --git a/python/setup.py b/python/setup.py
index c2769d0..e884acb 100755
--- a/python/setup.py
+++ b/python/setup.py
@@ -1,10 +1,14 @@
 #! /usr/bin/env python
 #
 # See README for usage instructions.
+from distutils import util
 import glob
 import os
+import pkg_resources
+import re
 import subprocess
 import sys
+import sysconfig
 import platform
 
 # We must use setuptools, not distutils, because we need to use the
@@ -185,6 +189,18 @@
     if sys.platform == 'darwin':
       extra_compile_args.append("-Wno-shorten-64-to-32");
 
+    # https://developer.apple.com/documentation/xcode_release_notes/xcode_10_release_notes
+    # C++ projects must now migrate to libc++ and are recommended to set a
+    # deployment target of macOS 10.9 or later, or iOS 7 or later.
+    if sys.platform == 'darwin':
+      mac_target = sysconfig.get_config_var('MACOSX_DEPLOYMENT_TARGET')
+      if mac_target and (pkg_resources.parse_version(mac_target) <
+                       pkg_resources.parse_version('10.9.0')):
+        os.environ['MACOSX_DEPLOYMENT_TARGET'] = '10.9'
+        os.environ['_PYTHON_HOST_PLATFORM'] = re.sub(
+            r'macosx-[0-9]+\.[0-9]+-(.+)', r'macosx-10.9-\1',
+            util.get_platform())
+
     # https://github.com/Theano/Theano/issues/4926
     if sys.platform == 'win32':
       extra_compile_args.append('-D_hypot=hypot')