diff --git a/contrib/ChangeLog b/contrib/ChangeLog
index 409f236df80..20b390db223 100644
--- a/contrib/ChangeLog
+++ b/contrib/ChangeLog
@@ -1,3 +1,10 @@
+2017-05-31  David Malcolm  <dmalcolm@redhat.com>
+	    Martin Liska  <mliska@suse.cz>
+
+	* filter_params.py: New, porting the perl script to python,
+	adding a test suite.
+	* filter_gcc_for_doxygen_new: New file.
+
 2017-05-30  Martin Liska  <mliska@suse.cz>
 
 	* analyze_brprob.py: Add new argument to parse and modify
diff --git a/contrib/filter_gcc_for_doxygen_new b/contrib/filter_gcc_for_doxygen_new
new file mode 100644
index 00000000000..d1109a50c88
--- /dev/null
+++ b/contrib/filter_gcc_for_doxygen_new
@@ -0,0 +1,12 @@
+#!/bin/sh
+
+# This filters GCC source before Doxygen can get confused by it;
+# this script is listed in the doxyfile.  The output is not very
+# pretty, but at least we get output that Doxygen can understand.
+#
+# $1 is a source file of some kind.  The source we wish doxygen to
+# process is put on stdout.
+
+dir=`dirname $0`
+python $dir/filter_params.py $1
+exit 0
diff --git a/contrib/filter_params.py b/contrib/filter_params.py
new file mode 100644
index 00000000000..f94d201bbf8
--- /dev/null
+++ b/contrib/filter_params.py
@@ -0,0 +1,144 @@
+#!/usr/bin/python
+"""
+Filters out some of the #defines used throughout the GCC sources:
+- GTY(()) marks declarations for gengtype.c
+- PARAMS(()) is used for K&R compatibility. See ansidecl.h.
+
+When passed one or more filenames, acts on those files and prints the
+results to stdout.
+
+When run without a filename, runs a unit-testing suite.
+"""
+import re
+import sys
+import unittest
+
+# Optional whitespace
+OPT_WS = '\s*'
+
+def filter_src(text):
+    """
+    str -> str.  We operate on the whole of the source file at once
+    (rather than individual lines) so that we can have multiline
+    regexes.
+    """
+
+    # Convert C comments from GNU coding convention of:
+    #    /* FIRST_LINE
+    #       NEXT_LINE
+    #       FINAL_LINE.  */
+    # to:
+    #    /** @verbatim FIRST_LINE
+    #       NEXT_LINE
+    #       FINAL_LINE.  @endverbatim */
+    # so that doxygen will parse them.
+    #
+    # Only comments that begin on the left-most column are converted.
+    text = re.sub(r'^/\* ',
+                  r'/** @verbatim ',
+                  text,
+                  flags=re.MULTILINE)
+    text = re.sub(r'\*/',
+                  r' @endverbatim */',
+                  text)
+
+    # Remove GTY markings (potentially multiline ones):
+    text = re.sub('GTY' + OPT_WS + r'\(\(.*?\)\)\s+',
+                  '',
+                  text,
+                  flags=(re.MULTILINE|re.DOTALL))
+
+    # Strip out 'ATTRIBUTE_UNUSED'
+    text = re.sub('\sATTRIBUTE_UNUSED',
+                  '',
+                  text)
+
+    # PARAMS(()) is used for K&R compatibility. See ansidecl.h.
+    text = re.sub('PARAMS' + OPT_WS + r'\(\((.*?)\)\)',
+                  r'(\1)',
+                  text)
+
+    return text
+
+class FilteringTests(unittest.TestCase):
+    '''
+    Unit tests for filter_src.
+    '''
+    def assert_filters_to(self, src_input, expected_result):
+        # assertMultiLineEqual was added to unittest in 2.7/3.1
+        if hasattr(self, 'assertMultiLineEqual'):
+            assertion = self.assertMultiLineEqual
+        else:
+            assertion = self.assertEqual
+        assertion(expected_result, filter_src(src_input))
+
+    def test_comment_example(self):
+        self.assert_filters_to(
+            ('/* FIRST_LINE\n'
+             '   NEXT_LINE\n'
+             '   FINAL_LINE.  */\n'),
+            ('/** @verbatim FIRST_LINE\n'
+             '   NEXT_LINE\n'
+             '   FINAL_LINE.   @endverbatim */\n'))
+
+    def test_oneliner_comment(self):
+        self.assert_filters_to(
+            '/* Returns the string representing CLASS.  */\n',
+            ('/** @verbatim Returns the string representing CLASS.   @endverbatim */\n'))
+
+    def test_multiline_comment(self):
+        self.assert_filters_to(
+            ('/* The thread-local storage model associated with a given VAR_DECL\n'
+             "   or SYMBOL_REF.  This isn't used much, but both trees and RTL refer\n"
+             "   to it, so it's here.  */\n"),
+            ('/** @verbatim The thread-local storage model associated with a given VAR_DECL\n'
+             "   or SYMBOL_REF.  This isn't used much, but both trees and RTL refer\n"
+             "   to it, so it's here.   @endverbatim */\n"))
+
+    def test_GTY(self):
+        self.assert_filters_to(
+            ('typedef struct GTY(()) alias_pair {\n'
+             '  tree decl;\n'
+             '  tree target;\n'
+             '} alias_pair;\n'),
+            ('typedef struct alias_pair {\n'
+             '  tree decl;\n'
+             '  tree target;\n'
+             '} alias_pair;\n'))
+
+    def test_multiline_GTY(self):
+        # Ensure that a multiline GTY is filtered out.
+        self.assert_filters_to(
+            ('class GTY((desc ("%h.type"), tag ("SYMTAB_SYMBOL"),\n'
+             '\t   chain_next ("%h.next"), chain_prev ("%h.previous")))\n'
+             '  symtab_node_base\n'
+             '{\n'),
+            ('class symtab_node_base\n'
+             '{\n'))
+
+    def test_ATTRIBUTE_UNUSED(self):
+        # Ensure that ATTRIBUTE_UNUSED is filtered out.
+        self.assert_filters_to(
+            ('static void\n'
+             'record_set (rtx dest, const_rtx set, void *data ATTRIBUTE_UNUSED)\n'
+             '{\n'),
+            ('static void\n'
+             'record_set (rtx dest, const_rtx set, void *data)\n'
+             '{\n'))
+
+    def test_PARAMS(self):
+        self.assert_filters_to(
+            'char *strcpy PARAMS ((char *dest, char *source));\n',
+            'char *strcpy (char *dest, char *source);\n')
+
+def act_on_files(argv):
+    for filename in argv[1:]:
+        with open(filename) as f:
+            text = f.read()
+            print(filter_src(text))
+
+if __name__ == '__main__':
+    if len(sys.argv) > 1:
+        act_on_files(sys.argv)
+    else:
+        unittest.main()