diff --git a/.circleci/config.yml b/.circleci/config.yml
index 53a1b061fb..2b2cd60c3d 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -1,4 +1,3 @@
-#adapted from https://raw.githubusercontent.com/ethereum-optimism/optimism/develop/.circleci/config.yml
 version: 2.1
 
 executors:
@@ -11,6 +10,19 @@ executors:
       DOCKER_BUILDKIT: 1
 
 commands:
+  check-changed:
+    description: "Conditionally halts a step if certain modules change"
+    parameters:
+      patterns:
+        type: string
+        description: "Comma-separated list of dependencies"
+    steps:
+      - run:
+          name: "Check for changes"
+          command: |
+            cd ops/check-changed
+            pip3 install -r requirements.txt
+            python3 main.py "<<parameters.patterns>>"
   download-solidity-compilers:
     steps:
       - checkout
@@ -53,6 +65,9 @@ commands:
         description: Folder to run tests in
         type: string
     steps:
+      - check-changed:
+          patterns: common-ts,contracts,core-utils,data-transport-layer,message-relayer,regenesis-surgery,sdk,integration-tests,l2geth,packages/boba/account-abstraction,packages/boba/bobalink,packages/boba/bundler,packages/boba/bundler_sdk,packages/boba/bundler_utils,packages/boba/contracts,packages/boba/gas-price-oracle,packages/boba/register,packages/boba/teleportation,ops,ops_boba
+
       - run:
           name: Build the project
           command: yarn && yarn build
@@ -140,15 +155,8 @@ jobs:
       - image: cimg/postgres:14.1
     steps:
       - checkout
-      - run:
-          name: Check if we should run
-          command: |
-            shopt -s inherit_errexit
-            CHANGED=$(check-changed "(<<parameters.working_directory>>|<<parameters.dependencies>>)" || echo "TRUE")
-            echo $CHANGED
-            if [[ "$CHANGED" = "FALSE" ]]; then
-              circleci step halt
-            fi
+      - check-changed:
+          patterns: go/proxyd
       - run:
           name: Lint
           command: golangci-lint run -E goimports,sqlclosecheck,bodyclose,asciicheck,misspell,errorlint -e "errors.As" -e "errors.Is" ./...
diff --git a/ops/check-changed/.gitignore b/ops/check-changed/.gitignore
new file mode 100644
index 0000000000..f5e96dbfae
--- /dev/null
+++ b/ops/check-changed/.gitignore
@@ -0,0 +1 @@
+venv
\ No newline at end of file
diff --git a/ops/check-changed/main.py b/ops/check-changed/main.py
new file mode 100644
index 0000000000..256d2163e4
--- /dev/null
+++ b/ops/check-changed/main.py
@@ -0,0 +1,134 @@
+import logging.config
+import os
+import re
+import subprocess
+import sys
+
+from github import Github
+
+REBUILD_ALL_PATTERNS = [
+    r'^\.circleci/\.*',
+    r'^\.github/\.*',
+    r'^package\.json',
+    r'^yarn\.lock',
+    r'ops/check-changed/.*'
+]
+
+WHITELISTED_BRANCHES = {
+    'master',
+    'develop'
+}
+
+LOGGING_CONFIG = {
+    'version': 1,
+    'disable_existing_loggers': True,
+    'formatters': {
+        'standard': {
+            'format': '%(asctime)s [%(levelname)s]: %(message)s'
+        },
+    },
+    'handlers': {
+        'default': {
+            'level': 'INFO',
+            'formatter': 'standard',
+            'class': 'logging.StreamHandler',
+            'stream': 'ext://sys.stderr'
+        },
+    },
+    'loggers': {
+        '': {
+            'handlers': ['default'],
+            'level': 'INFO',
+            'propagate': False
+        },
+    }
+}
+
+logging.config.dictConfig(LOGGING_CONFIG)
+log = logging.getLogger(__name__)
+
+
+def main():
+    patterns = sys.argv[1].split(',')
+    patterns = patterns + REBUILD_ALL_PATTERNS
+
+    fp = os.path.realpath(__file__)
+    monorepo_path = os.path.realpath(os.path.join(fp, '..', '..'))
+
+    log.info('Discovered monorepo path: %s', monorepo_path)
+    current_branch = git_cmd('rev-parse --abbrev-ref HEAD', monorepo_path)
+    log.info('Current branch: %s', current_branch)
+
+    if current_branch in WHITELISTED_BRANCHES:
+        log.info('Current branch %s is whitelisted, triggering build', current_branch)
+        exit_build()
+
+    pr_urls = os.getenv('CIRCLE_PULL_REQUESTS', None)
+    pr_urls = pr_urls.split(',') if pr_urls else []
+    if len(pr_urls) == 0:
+        log.info('Not a PR build, triggering build')
+        exit_build()
+    if len(pr_urls) > 1:
+        log.warning('Multiple PR URLs found, choosing the first one. PRs found:')
+        for url in pr_urls:
+            log.warning(url)
+
+    gh_token = os.getenv('GITHUB_ACCESS_TOKEN')
+    if gh_token is None:
+        log.info('No GitHub access token found - likely a fork. Triggering build')
+        exit_build()
+
+    g = Github(gh_token)
+    try:
+        g.get_user()
+        repo = g.get_repo(os.getenv('CIRCLE_PROJECT_USERNAME') + '/' + os.getenv('CIRCLE_PROJECT_REPONAME'))
+    except Exception:
+        log.exception('Failed to get repo from GitHub')
+        exit_build()
+
+    pr = repo.get_pull(int(pr_urls[0].split('/')[-1]))
+    log.info('Found PR: %s', pr.url)
+
+    base_sha = pr.base.sha
+    head_sha = pr.head.sha
+
+    diffs = git_cmd('diff --name-only {}...{}'.format(base_sha, head_sha), monorepo_path).split('\n')
+    log.info('Found diff. Checking for matches...')
+    for diff in diffs:
+        if match_path(diff, patterns):
+            log.info('Match found, triggering build')
+            exit_build()
+        else:
+            log.info('❌ no match found on %s', diff)
+
+    log.info('No matches found, skipping build')
+    exit_nobuild()
+
+
+def git_cmd(cmd, cwd):
+    return subprocess.check_output(['git'] + cmd.split(' '), cwd=cwd).decode('utf-8').strip()
+
+
+def match_path(path, patterns):
+    for pattern in patterns:
+        if re.search(pattern, path):
+            log.info('✅ match found on %s: %s', path, pattern)
+            return True
+    return False
+
+
+def exit_build():
+    sys.exit(0)
+
+
+def exit_nobuild():
+    subprocess.check_call(['circleci', 'step', 'halt'])
+    sys.exit(0)
+
+
+if __name__ == '__main__':
+    try:
+        main()
+    except Exception:
+        log.exception('Unhandled exception, triggering build')
+        exit_build()
diff --git a/ops/check-changed/requirements.txt b/ops/check-changed/requirements.txt
new file mode 100644
index 0000000000..0b1fcc85a0
--- /dev/null
+++ b/ops/check-changed/requirements.txt
@@ -0,0 +1,12 @@
+certifi==2022.12.7
+cffi==1.15.1
+charset-normalizer==2.1.1
+Deprecated==1.2.13
+idna==3.4
+pycparser==2.21
+PyGithub==1.57
+PyJWT==2.6.0
+PyNaCl==1.5.0
+requests==2.28.1
+urllib3==1.26.13
+wrapt==1.14.1