diff --git a/tools/deprecate_features/deprecate_features.py b/tools/deprecate_features/deprecate_features.py
index fd16c805d239f..3c88b1f2215ee 100644
--- a/tools/deprecate_features/deprecate_features.py
+++ b/tools/deprecate_features/deprecate_features.py
@@ -4,45 +4,98 @@
 import subprocess
 import fileinput
 
-grep_output = subprocess.check_output('grep -r "deprecated = true" api/*', shell=True)
-
-filenames_and_fields = set()
-
-# Compile the set of deprecated fields and the files they're in, deduping via set.
-deprecated_regex = re.compile(r'.*\/([^\/]*.proto):[^=]* ([^= ]+) =.*')
-for line in grep_output.splitlines():
-  match = deprecated_regex.match(line)
-  if match:
-    filenames_and_fields.add(tuple([match.group(1), match.group(2)]))
-  else:
-    print 'no match in ' + line + ' please address manually!'
-
-# Now discard any deprecated features already listed in runtime_features
-exiting_deprecated_regex = re.compile(r'.*"envoy.deprecated_features.(.*):(.*)",.*')
-with open('source/common/runtime/runtime_features.h', 'r') as features:
-  for line in features.readlines():
-    match = exiting_deprecated_regex.match(line)
+
+# Sorts out the list of deprecated proto fields which should be disallowed and returns a tuple of
+# email and code changes.
+def deprecate_proto():
+  grep_output = subprocess.check_output('grep -r "deprecated = true" api/*', shell=True)
+
+  filenames_and_fields = set()
+
+  # Compile the set of deprecated fields and the files they're in, deduping via set.
+  deprecated_regex = re.compile(r'.*\/([^\/]*.proto):[^=]* ([^= ]+) =.*')
+  for line in grep_output.splitlines():
+    match = deprecated_regex.match(line)
     if match:
-      filenames_and_fields.discard(tuple([match.group(1), match.group(2)]))
+      filenames_and_fields.add(tuple([match.group(1), match.group(2)]))
+    else:
+      print 'no match in ' + line + ' please address manually!'
+
+  # Now discard any deprecated features already listed in runtime_features
+  exiting_deprecated_regex = re.compile(r'.*"envoy.deprecated_features.(.*):(.*)",.*')
+  with open('source/common/runtime/runtime_features.cc', 'r') as features:
+    for line in features.readlines():
+      match = exiting_deprecated_regex.match(line)
+      if match:
+        filenames_and_fields.discard(tuple([match.group(1), match.group(2)]))
+
+  # Finally sort out the code to add to runtime_features.cc and a canned email for envoy-announce.
+  code_snippets = []
+  email_snippets = []
+  for (filename, field) in filenames_and_fields:
+    code_snippets.append('    "envoy.deprecated_features.' + filename + ':' + field + '",\n')
+    email_snippets.append(field + ' from ' + filename + '\n')
+  code = ''.join(code_snippets)
+  email = ''
+  if email_snippets:
+    email = ('\nThe following deprecated configuration fields will be disallowed by default:\n' +
+             ''.join(email_snippets))
 
-# Finally sort out the code to add to runtime_features.h and a canned email for envoy-announce.
-code = ''
-email = 'The latest Envoy release will deprecate the following configuration fields:\n'
-for (filename, field) in filenames_and_fields:
-  code += ('    "envoy.deprecated_features.' + filename + ':' + field + '",\n')
-  email += (field + ' from ' + filename + '\n')
+  return email, code
+
+
+# Sorts out the list of features which should be default enabled and returns a tuple of
+# email and code changes.
+def flip_runtime_features():
+  grep_output = subprocess.check_output(
+      'grep -r "envoy.reloadable_features\." source/*', shell=True)
+
+  features_to_flip = set()
+
+  # Compile the set of features to flip, deduping via set.
+  deprecated_regex = re.compile(r'.*"(envoy.reloadable_features\.[^"]+)".*')
+  for line in grep_output.splitlines():
+    match = deprecated_regex.match(line)
+    if match:
+      features_to_flip.add(match.group(1))
+    else:
+      print 'no match in ' + line + ' please address manually!'
 
-print '\n\nSuggested runtime changes: '
-print code
+  # Exempt the two test flags.
+  features_to_flip.remove('envoy.reloadable_features.my_feature_name')
+  features_to_flip.remove('envoy.reloadable_features.test_feature_true')
 
-if not raw_input('Apply runtime changes? [yN] ').strip().lower() in ('y', 'yes'):
+  code_snippets = []
+  email_snippets = []
+  for (feature) in features_to_flip:
+    code_snippets.append('    "' + feature + '",\n')
+    email_snippets.append(feature + '\n')
+  code = ''.join(code_snippets)
+  email = ''
+  if email_snippets:
+    email = 'the following features will be defaulted to true:\n' + ''.join(email_snippets)
+
+  return email, code
+
+
+# Gather code and suggested email changes.
+runtime_email, runtime_features_code = flip_runtime_features()
+deprecate_email, deprecate_code = deprecate_proto()
+
+email = ('The Envoy maintainer team is cutting the next Envoy release.  In the new release ' +
+         runtime_email + deprecate_email)
+
+print '\n\nSuggested envoy-announce email: \n'
+print email
+
+if not raw_input('Apply relevant runtime changes? [yN] ').strip().lower() in ('y', 'yes'):
   exit(1)
 
-for line in fileinput.FileInput('source/common/runtime/runtime_features.h', inplace=1):
+for line in fileinput.FileInput('source/common/runtime/runtime_features.cc', inplace=1):
+  if 'envoy.reloadable_features.test_feature_true' in line:
+    line = line.replace(line, line + runtime_features_code)
   if 'envoy.deprecated_features.deprecated.proto:is_deprecated_fatal' in line:
-    line = line.replace(line, line + code)
+    line = line.replace(line, line + deprecate_code)
   print line,
 
-print '\nChanges applied.  Please create an upstream PR and send the following to envoy-announce:\n'
-
-print email
+print '\nChanges applied.  Please send the email above to envoy-announce.\n'