diff --git a/libc/tools/check-symbols-glibc.py b/libc/tools/check-symbols-glibc.py
new file mode 100755
index 0000000..43b213f
--- /dev/null
+++ b/libc/tools/check-symbols-glibc.py
@@ -0,0 +1,120 @@
+#!/usr/bin/python
+
+import glob
+import os
+import re
+import string
+import subprocess
+import sys
+
+toolchain = os.environ['ANDROID_TOOLCHAIN']
+arch = re.sub(r'.*/linux-x86/([^/]+)/.*', r'\1', toolchain)
+
+def GetSymbolsFromSo(so_file):
+
+  # Example readelf output:
+  #   264: 0001623c     4 FUNC    GLOBAL DEFAULT    8 cabsf
+  #   266: 00016244     4 FUNC    GLOBAL DEFAULT    8 dremf
+  #   267: 00019018     4 OBJECT  GLOBAL DEFAULT   11 __fe_dfl_env
+  #   268: 00000000     0 FUNC    GLOBAL DEFAULT  UND __aeabi_dcmplt
+
+  r = re.compile(r' +\d+: [0-9a-f]+ +\d+ (I?FUNC|OBJECT) +\S+ +\S+ +\d+ (\S+)')
+
+  symbols = set()
+
+  for line in subprocess.check_output(['readelf', '--dyn-syms', '-W', so_file]).split('\n'):
+     if ' HIDDEN ' in line or ' UND ' in line:
+       continue
+     m = r.match(line)
+     if m:
+       symbol = m.group(2)
+       symbol = re.sub('@.*', '', symbol)
+       symbols.add(symbol)
+
+  return symbols
+
+def GetSymbolsFromAndroidSo(*files):
+  symbols = set()
+  for f in files:
+    symbols = symbols | GetSymbolsFromSo('%s/system/lib64/%s' % (os.environ['ANDROID_PRODUCT_OUT'], f))
+  return symbols
+
+def GetSymbolsFromSystemSo(*files):
+  symbols = set()
+  for f in files:
+    f = glob.glob('/lib/x86_64-linux-gnu/%s' % f)[-1]
+    symbols = symbols | GetSymbolsFromSo(f)
+  return symbols
+
+glibc = GetSymbolsFromSystemSo('libc.so.*', 'librt.so.*', 'libpthread.so.*', 'libresolv.so.*', 'libm.so.*')
+bionic = GetSymbolsFromAndroidSo('libc.so', 'libm.so')
+
+# bionic includes various BSD symbols to ease porting other BSD-licensed code.
+bsd_stuff = set([
+  'getprogname',
+  'setprogname',
+  'strlcat',
+  'strlcpy',
+  'wcslcat',
+  'wcslcpy'
+])
+# Some symbols are part of the FORTIFY implementation.
+FORTIFY_stuff = set([
+  '__FD_CLR_chk',
+  '__FD_ISSET_chk',
+  '__FD_SET_chk',
+  '__stack_chk_guard',
+  '__stpncpy_chk2',
+  '__strchr_chk',
+  '__strlcat_chk',
+  '__strlcpy_chk',
+  '__strlen_chk',
+  '__strncpy_chk2',
+  '__strrchr_chk',
+  '__umask_chk'
+])
+# bionic exposes various Linux features that glibc doesn't.
+linux_stuff = set([
+  'getauxval',
+  'gettid',
+  'tgkill'
+])
+# Some standard stuff isn't yet in the versions of glibc we're using.
+std_stuff = set([
+  'at_quick_exit'
+])
+# These have mangled names in glibc, with a macro taking the "obvious" name.
+weird_stuff = set([
+  'fstat',
+  'fstat64',
+  'fstatat',
+  'fstatat64',
+  'isfinite',
+  'isfinitef',
+  'isfinitel',
+  'isnormal',
+  'isnormalf',
+  'isnormall',
+  'lstat',
+  'lstat64',
+  'mknod',
+  'mknodat',
+  'stat',
+  'stat64',
+])
+
+print 'glibc:'
+for symbol in sorted(glibc):
+  print symbol
+
+print
+print 'bionic:'
+for symbol in sorted(bionic):
+  print symbol
+
+print
+print 'in bionic but not glibc:'
+for symbol in sorted((bionic - bsd_stuff - FORTIFY_stuff - linux_stuff - std_stuff - weird_stuff).difference(glibc)):
+  print symbol
+
+sys.exit(0)