diff --git a/.dockerignore b/.dockerignore
new file mode 100644
index 000000000..61ac0b13e
--- /dev/null
+++ b/.dockerignore
@@ -0,0 +1,10 @@
+out
+.git
+
+# Copied from .gitignore.
+.vscode/
+*.pyc
+/build/
+*~
+.DS_Store
+*.swp
diff --git a/infra/cifuzz/actions/build_fuzzers/build_fuzzers_entrypoint.py b/infra/cifuzz/actions/build_fuzzers/build_fuzzers_entrypoint.py
index 74cd2d495..f46e6390e 100644
--- a/infra/cifuzz/actions/build_fuzzers/build_fuzzers_entrypoint.py
+++ b/infra/cifuzz/actions/build_fuzzers/build_fuzzers_entrypoint.py
@@ -97,7 +97,8 @@ def main():
 
   out_dir = os.path.join(workspace, 'out')
   if cifuzz.check_fuzzer_build(out_dir, sanitizer=sanitizer):
-    return 0
+    returncode = 0
+
   return returncode
 
 
diff --git a/infra/cifuzz/cifuzz-base/Dockerfile b/infra/cifuzz/cifuzz-base/Dockerfile
index ecb889a01..3d887b4d5 100644
--- a/infra/cifuzz/cifuzz-base/Dockerfile
+++ b/infra/cifuzz/cifuzz-base/Dockerfile
@@ -34,4 +34,4 @@ RUN add-apt-repository \
 RUN apt-get update && apt-get install docker-ce docker-ce-cli containerd.io -y
 
 ENV OSS_FUZZ_ROOT=/opt/oss-fuzz
-RUN git clone https://github.com/google/oss-fuzz.git ${OSS_FUZZ_ROOT}
+ADD . ${OSS_FUZZ_ROOT}
diff --git a/infra/cifuzz/cifuzz.py b/infra/cifuzz/cifuzz.py
index 1d3d0e2f7..e20dc45ac 100644
--- a/infra/cifuzz/cifuzz.py
+++ b/infra/cifuzz/cifuzz.py
@@ -79,6 +79,20 @@ logging.basicConfig(
     level=logging.DEBUG)
 
 
+def checkout_specified_commit(build_repo_manager, pr_ref, commit_sha):
+  """Checks out the specified commit or pull request using
+  build_repo_manager."""
+  try:
+    if pr_ref:
+      build_repo_manager.checkout_pr(pr_ref)
+    else:
+      build_repo_manager.checkout_commit(commit_sha)
+  except (RuntimeError, ValueError):
+    logging.error(
+        'Can not check out requested state %s. '
+        'Using current repo state', pr_ref or commit_sha)
+
+
 # pylint: disable=too-many-arguments
 # pylint: disable=too-many-locals
 def build_fuzzers(project_name,
@@ -109,34 +123,40 @@ def build_fuzzers(project_name,
 
   logging.info("Using %s sanitizer.", sanitizer)
 
-  git_workspace = os.path.join(workspace, 'storage')
-  os.makedirs(git_workspace, exist_ok=True)
   out_dir = os.path.join(workspace, 'out')
   os.makedirs(out_dir, exist_ok=True)
 
-  # Detect repo information.
-  inferred_url, oss_fuzz_repo_path = build_specified_commit.detect_main_repo(
-      project_name, repo_name=project_repo_name)
-  if not inferred_url or not oss_fuzz_repo_path:
+  # Build Fuzzers using docker run.
+  inferred_url, project_builder_repo_path = (
+      build_specified_commit.detect_main_repo(project_name,
+                                              repo_name=project_repo_name))
+  if not inferred_url or not project_builder_repo_path:
     logging.error('Could not detect repo from project %s.', project_name)
     return False
-  src_in_docker = os.path.dirname(oss_fuzz_repo_path)
-  oss_fuzz_repo_name = os.path.basename(oss_fuzz_repo_path)
+  project_repo_name = os.path.basename(project_builder_repo_path)
+  src_in_project_builder = os.path.dirname(project_builder_repo_path)
+
+  manual_src_path = os.getenv('MANUAL_SRC_PATH')
+  if manual_src_path:
+    if not os.path.exists(manual_src_path):
+      logging.error(
+          'MANUAL_SRC_PATH: %s does not exist. '
+          'Are you mounting it correctly?', manual_src_path)
+      return False
+    # This is the path taken outside of GitHub actions.
+    git_workspace = os.path.dirname(manual_src_path)
+  else:
+    git_workspace = os.path.join(workspace, 'storage')
+    os.makedirs(git_workspace, exist_ok=True)
 
   # Checkout projects repo in the shared volume.
   build_repo_manager = repo_manager.RepoManager(inferred_url,
                                                 git_workspace,
-                                                repo_name=oss_fuzz_repo_name)
-  try:
-    if pr_ref:
-      build_repo_manager.checkout_pr(pr_ref)
-    else:
-      build_repo_manager.checkout_commit(commit_sha)
-  except (RuntimeError, ValueError):
-    logging.error('Can not check out requested state %s.', pr_ref or commit_sha)
-    logging.error('Using current repo state.')
+                                                repo_name=project_repo_name)
+
+  if not manual_src_path:
+    checkout_specified_commit(build_repo_manager, pr_ref, commit_sha)
 
-  # Build Fuzzers using docker run.
   command = [
       '--cap-add',
       'SYS_PTRACE',
@@ -153,13 +173,14 @@ def build_fuzzers(project_name,
   if container:
     command += ['-e', 'OUT=' + out_dir, '--volumes-from', container]
     bash_command = 'rm -rf {0} && cp -r {1} {2} && compile'.format(
-        os.path.join(src_in_docker, oss_fuzz_repo_name, '*'),
-        os.path.join(git_workspace, oss_fuzz_repo_name), src_in_docker)
+        os.path.join(src_in_project_builder, project_repo_name, '*'),
+        os.path.join(git_workspace, project_repo_name), src_in_project_builder)
   else:
     command += [
         '-e', 'OUT=' + '/out', '-v',
-        '%s:%s' % (os.path.join(git_workspace, oss_fuzz_repo_name),
-                   os.path.join(src_in_docker, oss_fuzz_repo_name)), '-v',
+        '%s:%s' % (os.path.join(git_workspace, project_repo_name),
+                   os.path.join(src_in_project_builder, project_repo_name)),
+        '-v',
         '%s:%s' % (out_dir, '/out')
     ]
     bash_command = 'compile'
@@ -175,7 +196,7 @@ def build_fuzzers(project_name,
     return False
   remove_unaffected_fuzzers(project_name, out_dir,
                             build_repo_manager.get_git_diff(),
-                            oss_fuzz_repo_path)
+                            project_builder_repo_path)
   return True