Index: llvm/test/tools/UpdateTestChecks/lit.local.cfg
===================================================================
--- llvm/test/tools/UpdateTestChecks/lit.local.cfg
+++ llvm/test/tools/UpdateTestChecks/lit.local.cfg
@@ -16,7 +16,8 @@
     script_path = os.path.join(config.llvm_src_root, 'utils', name[1:] + '.py')
     assert os.path.isfile(script_path)
     config.substitutions.append(
-        (name, "'%s' %s %s" % (python_exe, script_path, extra_args)))
+        (name, "'%s' %s %s" % (
+            config.python_executable, script_path, extra_args)))
 
 
 config.test_format = lit.formats.ShTest(execute_external=False)
@@ -43,20 +44,12 @@
     mca_arg = '--llvm-mca-binary ' + shell_quote(llvm_mca_path)
     add_update_script_substition('%update_test_checks', extra_args=mca_arg)
 
-# update_cc_test_checks requires python3
-py3_exe = lit.util.which('python3')
-if py3_exe:
-    config.substitutions.append(('%python3', shell_quote(py3_exe)))
-    config.available_features.add('python3')
-
 clang_path = os.path.join(config.llvm_tools_dir, 'clang')
 if os.path.isfile(clang_path):
     config.available_features.add('clang-binary')
-    if py3_exe:
-        # XXX: or use --llvm-bin?
-        extra_args = '--clang ' + shell_quote(clang_path)
-        if os.path.isfile(opt_path):
-            extra_args += ' --opt ' + shell_quote(opt_path)
-        add_update_script_substition('%update_cc_test_checks',
-                                     python_exe=py3_exe,
-                                     extra_args=extra_args)
+    # XXX: or use --llvm-bin?
+    extra_args = '--clang ' + shell_quote(clang_path)
+    if os.path.isfile(opt_path):
+        extra_args += ' --opt ' + shell_quote(opt_path)
+    add_update_script_substition('%update_cc_test_checks',
+                                 extra_args=extra_args)
Index: llvm/test/tools/UpdateTestChecks/update_cc_test_checks/mangled_names.test
===================================================================
--- llvm/test/tools/UpdateTestChecks/update_cc_test_checks/mangled_names.test
+++ llvm/test/tools/UpdateTestChecks/update_cc_test_checks/mangled_names.test
@@ -1,10 +1,6 @@
 ## Basic test checking that update_cc_test_checks.py works as expected for
 ## functions with mangled names
 
-# %update_cc_test_checks is only set if python3 is on the path.
-# FIXME: Is this the best approach? See discussion on D70660.
-# REQUIRES: python3
-
 # RUN: cp -f %S/Inputs/mangled_names.c %t.c && %update_cc_test_checks -v %t.c
 # RUN: diff -u %t.c %S/Inputs/mangled_names.c.expected
 ## Check that running the script again does not change the result:
Index: llvm/utils/update_cc_test_checks.py
===================================================================
--- llvm/utils/update_cc_test_checks.py
+++ llvm/utils/update_cc_test_checks.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 '''A utility to update LLVM IR CHECK lines in C/C++ FileCheck test files.
 
 Example RUN lines in .c/.cc test files:
@@ -12,6 +12,8 @@
 % utils/update_cc_test_checks.py --clang=release/bin/clang /tmp/c/a.cc
 '''
 
+from __future__ import print_function
+
 import argparse
 import collections
 import distutils.spawn
@@ -37,18 +39,21 @@
 def get_line2spell_and_mangled(args, clang_args):
   ret = {}
   # Use clang's JSON AST dump to get the mangled name
-  json_dump_args = [args.clang, *clang_args, '-fsyntax-only', '-o', '-']
+  json_dump_args = [args.clang] + clang_args + ['-fsyntax-only', '-o', '-']
   if '-cc1' not in json_dump_args:
     # For tests that invoke %clang instead if %clang_cc1 we have to use
     # -Xclang -ast-dump=json instead:
     json_dump_args.append('-Xclang')
   json_dump_args.append('-ast-dump=json')
   common.debug('Running', ' '.join(json_dump_args))
-  status = subprocess.run(json_dump_args, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-  if status.returncode != 0:
+
+  popen = subprocess.Popen(json_dump_args, stdout=subprocess.PIPE,
+                           stderr=subprocess.PIPE, universal_newlines=True)
+  stdout, stderr = popen.communicate()
+  if popen.returncode != 0:
     sys.stderr.write('Failed to run ' + ' '.join(json_dump_args) + '\n')
-    sys.stderr.write(status.stderr.decode())
-    sys.stderr.write(status.stdout.decode())
+    sys.stderr.write(stderr)
+    sys.stderr.write(stdout)
     sys.exit(2)
 
   # Parse the clang JSON and add all children of type FunctionDecl.
@@ -75,7 +80,7 @@
     mangled = node.get('mangledName', spell)
     ret[int(line)-1] = (spell, mangled)
 
-  ast = json.loads(status.stdout.decode())
+  ast = json.loads(stdout)
   if ast['kind'] != 'TranslationUnitDecl':
     common.error('Clang AST dump JSON format changed?')
     sys.exit(2)