diff --git a/Doc/library/os.rst b/Doc/library/os.rst
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -219,6 +219,17 @@
    .. versionadded:: 3.2
 
 
+.. function:: get_shell_executable()
+
+   Return a path to the standard system shell executable -- ``sh``
+   program on POSIX (default: ``'/bin/sh'``) or ``%ComSpec%`` command
+   processor on Windows (default: ``%SystemRoot%\system32\cmd.exe``).
+
+   Availability: Unix, Windows
+
+   .. versionadded:: 3.5
+
+
 .. function:: getegid()
 
    Return the effective group id of the current process.  This corresponds to the
diff --git a/Lib/os.py b/Lib/os.py
--- a/Lib/os.py
+++ b/Lib/os.py
@@ -612,6 +612,29 @@
     return path_list.split(pathsep)
 
 
+if sys.platform == "win32": # use sys.platform to accommodate java
+    def get_shell_executable():
+        """Return path to the command processor specified by %ComSpec%.
+
+        Default: %SystemRoot%\system32\cmd.exe
+        """
+        return (environ.get('ComSpec') or
+                path.join(environ.get('SystemRoot', r'C:\Windows'),
+                          r'system32\cmd.exe'))
+else: # POSIX
+    def get_shell_executable():
+        """Return path to the standard system shell executable.
+
+        Default: '/bin/sh'
+        """
+        for dirpath in defpath.split(pathsep):
+            sh = dirpath + sep + 'sh' #NOTE: interpret '' as '/'
+            if access(sh, F_OK | X_OK) and path.isfile(sh):
+                #NOTE: allow symlinks e.g., /bin/sh on Ubuntu may be dash
+                return sh
+        return '/bin/sh' #XXX either OS or python are broken if we got here
+
+
 # Change environ to automatically call putenv(), unsetenv if they exist.
 from _collections_abc import MutableMapping
 
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -734,6 +734,35 @@
         self.assertTrue(cm.exception.__suppress_context__)
 
 
+class ShellExecutableTests(unittest.TestCase):
+    # test os.get_shell_executable()
+    def _test_get_shell_executable(self, env):
+        saved_environ = os.environ
+        try:
+            os.environ = env # test with env environment
+            sh = os.get_shell_executable()
+            self.assertTrue(sh) # not empty, not None
+            self.assertTrue(os.path.exists(sh))
+            option = "/c" if sys.platform == 'win32' else "-c"
+            #NOTE: `exit` should work even with an empty environment
+            self.assertEqual(subprocess.call([sh, option, "exit 5"]), 5)
+        finally:
+            os.environ = saved_environ
+
+    def test_get_shell_executable(self):
+        self._test_get_shell_executable(os.environ)
+
+    def test_get_shell_executable_invalid_nonempty_path(self):
+        env = {'SystemRoot': os.environ.get('SystemRoot'),
+               'PATH': '\0'}
+        self._test_get_shell_executable(env)
+
+    @unittest.skipIf(sys.platform == 'win32',
+                     "Empty env. is not supported on Win32")
+    def test_get_shell_executable_empty_environment(self):
+        self._test_get_shell_executable({})
+
+
 class WalkTests(unittest.TestCase):
     """Tests for os.walk()."""
 
@@ -2622,6 +2651,7 @@
         FileTests,
         StatAttributeTests,
         EnvironTests,
+        ShellExecutableTests,
         WalkTests,
         FwalkTests,
         MakedirTests,