diff --git a/README.md b/README.md
index af2f1c3..dfe6e1a 100644
--- a/README.md
+++ b/README.md
@@ -54,6 +54,7 @@ MS_GITHUB_TOKEN=abc123 php run.php update --cms-major=5 --branch=next-minor --dr
 | --dry-run | Do not push to github or create pull-requests |
 | --account | GitHub account to use for creating pull-requests (default: creative-commoners) |
 | --no-delete | Do not delete `_data` and `_modules` directories before running |
+| --unsupported | Only update unsupported modules that were supported in the previous CMS major. Must also use `--branch=default-branch`. Can not be used with `--cms-major` option. |
 | --update-prs | Update existing open PRs instead of creating new PRs |
 
 **Note** that using `--branch=github-default` will only run scripts in the `scripts/default-branch` directory.
diff --git a/funcs_scripts.php b/funcs_scripts.php
index 1fe20a6..2f84594 100644
--- a/funcs_scripts.php
+++ b/funcs_scripts.php
@@ -138,6 +138,20 @@ function module_is_recipe()
     return ($json->type ?? '') === 'silverstripe-recipe';
 }
 
+/**
+ * Determine if the module being processed is supported for the current $CMS_MAJOR
+ *
+ * Example usage:
+ * module_is_supported()
+ */
+function module_is_supported()
+{
+    global $GITHUB_REF, $CMS_MAJOR;
+    $repoMetaData = MetaData::getMetaDataForRepository($GITHUB_REF);
+    $metaData = MetaData::removeReposNotInCmsMajor([$repoMetaData], $CMS_MAJOR);
+    return count($metaData) > 0;
+}
+
 /**
  * Determine if the repository being processed is an actual silverstripe module e.g. silverstripe-admin, not gha-*
  *
diff --git a/funcs_utils.php b/funcs_utils.php
index edccfa6..ce18529 100644
--- a/funcs_utils.php
+++ b/funcs_utils.php
@@ -380,6 +380,24 @@ function filtered_modules($cmsMajor, $input)
         $cmsMajor === MetaData::HIGHEST_STABLE_CMS_MAJOR
     );
 
+    if ($input->getOption('unsupported')) {
+        $prevCmsMajor = $cmsMajor - 1;
+        $prevCmsRepos = MetaData::removeReposNotInCmsMajor(
+            MetaData::getAllRepositoryMetaData(false),
+            $prevCmsMajor,
+            false
+        );
+        $repoGithubs = array_map(fn($repo) => $repo['github'], $repos);
+        $unsupportedRepos = [];
+        foreach ($prevCmsRepos as $prevCmsRepo) {
+            if (in_array($prevCmsRepo['github'], $repoGithubs)) {
+                continue;
+            }
+            $unsupportedRepos[] = $prevCmsRepo;
+        }
+        $repos = $unsupportedRepos;
+    }
+
     $modules = convert_repos_data_to_modules($repos);
 
     if ($input->getOption('only')) {
diff --git a/run.php b/run.php
index 1222dc0..6e99397 100644
--- a/run.php
+++ b/run.php
@@ -27,6 +27,7 @@
 const TAG_RULESET_NAME = 'Silverstripe CMS tag ruleset';
 
 // global variables
+$CMS_MAJOR = '';
 $MODULE_DIR = '';
 $GITHUB_REF = '';
 $PRS_CREATED = [];
@@ -80,6 +81,12 @@
     InputOption::VALUE_NONE,
     'Do not delete _data and _modules directories before running'
 ];
+$optionUnsupported = [
+    'unsupported',
+    null,
+    InputOption::VALUE_NONE,
+    'Only update unsupported modules that were supported in the previous CMS major. Must also use --branch=default-branch. Can not be used with --cms-major option.'
+];
 $optionUpdatePrs = [
     'update-prs',
     null,
@@ -98,6 +105,7 @@
     ->addOption(...$optionDryRun)
     ->addOption(...$optionAccount)
     ->addOption(...$optionNoDelete)
+    ->addOption(...$optionUnsupported)
     ->addOption(...$optionUpdatePrs)
     ->setCode($updateCommand);
 
diff --git a/scripts/default-branch/readme.php b/scripts/default-branch/readme.php
new file mode 100644
index 0000000..0aa0548
--- /dev/null
+++ b/scripts/default-branch/readme.php
@@ -0,0 +1,8 @@
+<?php
+
+if (!module_is_supported() && file_exists('README.md')) {
+    $contents = read_file('README.md');
+    $rx = "#\n\[!\[Silverstripe supported module\].+?\n#s";
+    $contents = preg_replace($rx, "\n", $contents);
+    write_file_even_if_exists('README.md', $contents);
+}
diff --git a/update_command.php b/update_command.php
index f50b518..ff9a57f 100644
--- a/update_command.php
+++ b/update_command.php
@@ -9,7 +9,7 @@
     // This is the code that is executed when running the 'update' command
 
     // variables
-    global $MODULE_DIR, $GITHUB_REF, $OUT, $PRS_CREATED, $REPOS_WITH_PRS_CREATED;
+    global $MODULE_DIR, $GITHUB_REF, $OUT, $PRS_CREATED, $REPOS_WITH_PRS_CREATED, $CMS_MAJOR;
     $OUT = $output;
 
     // validate system is ready
@@ -18,6 +18,16 @@
     // setup directories
     setup_directories($input);
 
+    // unsupported option must be used with github-default option
+    if ($input->getOption('unsupported') && $input->getOption('branch') !== 'github-default') {
+        error('The --unsupported option must be used with --branch=github-default');
+    }
+
+    // unsupported option must not be used with cms-major option
+    if ($input->getOption('unsupported') && $input->getOption('cms-major')) {
+        error('The --unsupported option must not be used with the --cms-major option');
+    }
+
     // branch
     $branchOption = $input->getOption('branch') ?: DEFAULT_BRANCH;
     if (!in_array($branchOption, BRANCH_OPTIONS)) {
@@ -25,10 +35,10 @@
     }
 
     // CMS major version to use
-    $cmsMajor = $input->getOption('cms-major') ?: MetaData::HIGHEST_STABLE_CMS_MAJOR;
+    $CMS_MAJOR = $input->getOption('cms-major') ?: MetaData::HIGHEST_STABLE_CMS_MAJOR;
 
     // modules
-    $modules = filtered_modules($cmsMajor, $input);
+    $modules = filtered_modules($CMS_MAJOR, $input);
 
     // script files
     if ($branchOption === 'github-default') {
@@ -36,7 +46,7 @@
     } else {
         $scriptFiles = array_merge(
             script_files('any'),
-            script_files($cmsMajor),
+            script_files($CMS_MAJOR),
         );
     }
 
@@ -131,7 +141,7 @@
                     $defaultBranch,
                     $currentBranch,
                     $currentBranchCmsMajor,
-                    $cmsMajor,
+                    $CMS_MAJOR,
                     $branchOption
                 );
             }
@@ -142,8 +152,8 @@
         cmd("git checkout $branchToCheckout", $MODULE_DIR);
 
         // ensure that this branch actually supports the cmsMajor we're targetting
-        if (!$useDefaultBranch && $branchOption !== 'github-default' && current_branch_cms_major() !== $cmsMajor) {
-            error("Branch $branchToCheckout does not support CMS major version $cmsMajor");
+        if (!$useDefaultBranch && $branchOption !== 'github-default' && current_branch_cms_major() !== $CMS_MAJOR) {
+            error("Branch $branchToCheckout does not support CMS major version $CMS_MAJOR");
         }
 
         // create a new branch used for the pull-request