Index: Doc/using/cmdline.rst
===================================================================
--- Doc/using/cmdline.rst	(revision 77505)
+++ Doc/using/cmdline.rst	(working copy)
@@ -353,6 +353,8 @@
       :mod:`warnings` -- the warnings module
 
       :pep:`230` -- Warning framework
+      
+      :envvar:`PYTHONWARNINGS`
 
 
 .. cmdoption:: -x
@@ -528,8 +530,13 @@
    If this environment variable is set, ``sys.argv[0]`` will be set to its
    value instead of the value got through the C runtime.  Only works on
    Mac OS X.
+   
+.. envvar:: PYTHONWARNINGS
 
+   This is the equivalent to the :option:`-W` option. If set to a comma
+   separated string, it is equivalent to specifying :option:`-W` multiple times.
 
+
 Debug-mode variables
 ~~~~~~~~~~~~~~~~~~~~
 
Index: Lib/test/test_warnings.py
===================================================================
--- Lib/test/test_warnings.py	(revision 77505)
+++ Lib/test/test_warnings.py	(working copy)
@@ -4,6 +4,7 @@
 import StringIO
 import sys
 import unittest
+import subprocess
 from test import test_support
 
 import warning_tests
@@ -655,6 +656,42 @@
     module = py_warnings
 
 
+class EnvironmentVariableTests(BaseTest):
+
+    def test_single_warning(self):
+        newenv = os.environ.copy()
+        newenv["PYTHONWARNINGS"] = "ignore::DeprecationWarning"
+        p = subprocess.Popen(sys.executable +
+                    ' -c "import sys; sys.stdout.write(str(sys.warnoptions))"',
+                             stdout=subprocess.PIPE, env=newenv)
+        self.assertEqual(p.stdout.read(), "['ignore::DeprecationWarning']")
+        
+    def test_comma_separated_warnings(self):
+        newenv = os.environ.copy()
+        newenv["PYTHONWARNINGS"] = ("ignore::DeprecationWarning,"
+                                    "ignore::UnicodeWarning")
+        p = subprocess.Popen(sys.executable +
+                    ' -c "import sys; sys.stdout.write(str(sys.warnoptions))"',
+                             stdout=subprocess.PIPE, env=newenv)
+        self.assertEqual(p.stdout.read(),
+                    "['ignore::DeprecationWarning', 'ignore::UnicodeWarning']")
+
+    def test_envvar_and_command_line(self):
+        newenv = os.environ.copy()
+        newenv["PYTHONWARNINGS"] = "ignore::DeprecationWarning"
+        p = subprocess.Popen(sys.executable + (" -W ignore::UnicodeWarning"
+                    ' -c "import sys; sys.stdout.write(str(sys.warnoptions))"'),
+                             stdout=subprocess.PIPE, env=newenv)
+        self.assertEqual(p.stdout.read(),
+                    "['ignore::UnicodeWarning', 'ignore::DeprecationWarning']")
+
+class CEnvironmentVariableTests(EnvironmentVariableTests):
+    module = c_warnings
+
+class PyEnvironmentVariableTests(EnvironmentVariableTests):
+    module = py_warnings
+    
+
 def test_main():
     py_warnings.onceregistry.clear()
     c_warnings.onceregistry.clear()
@@ -664,6 +701,8 @@
                                 _WarningsTests,
                                 CWarningsDisplayTests, PyWarningsDisplayTests,
                                 CCatchWarningTests, PyCatchWarningTests,
+                                CEnvironmentVariableTests,
+                                PyEnvironmentVariableTests
                              )
 
 
Index: Modules/main.c
===================================================================
--- Modules/main.c	(revision 77505)
+++ Modules/main.c	(working copy)
@@ -83,6 +83,7 @@
          can be supplied multiple times to increase verbosity\n\
 -V     : print the Python version number and exit (also --version)\n\
 -W arg : warning control; arg is action:message:category:module:lineno\n\
+         also PYTHONWARNINGS=arg\n\
 -x     : skip first line of source, allowing use of non-Unix forms of #!cmd\n\
 ";
 static char *usage_4 = "\
@@ -420,6 +421,16 @@
 	    (p = Py_GETENV("PYTHONNOUSERSITE")) && *p != '\0')
 		Py_NoUserSiteDirectory = 1;
 
+	if ((p = Py_GETENV("PYTHONWARNINGS")) && *p != '\0')
+	{
+		char* warning = strtok(p, ",");
+		while (warning != NULL)
+		{
+			PySys_AddWarnOption(warning);
+			warning = strtok(NULL, ",");
+		}
+	}
+
 	if (command == NULL && module == NULL && _PyOS_optind < argc &&
 	    strcmp(argv[_PyOS_optind], "-") != 0)
 	{