diff --git a/pyproject.toml b/pyproject.toml
index e4e9c489..cb8ec79c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -71,6 +71,7 @@ oca-update-pre-commit-excluded-addons = "tools.update_pre_commit_excluded_addons
 oca-fix-manifest-website = "tools.fix_manifest_website:main"
 oca-configure-travis= "tools.configure_travis:main"
 oca-copier-update = "tools.copier_update:main"
+oca-create-branch-from-previous = "tools.create_branch_from_previous:main"
 
 [tool.hatch.build.targets.wheel]
 packages = ["tools"]
diff --git a/tests/test_mark_modules_uninstallable.py b/tests/test_mark_modules_uninstallable.py
new file mode 100644
index 00000000..80650454
--- /dev/null
+++ b/tests/test_mark_modules_uninstallable.py
@@ -0,0 +1,50 @@
+import textwrap
+
+from tools.manifest import mark_modules_uninstallable, mark_manifest_uninstallable
+
+
+def test_mark_module_uninstallable(tmp_path):
+    (tmp_path / "mod1").mkdir()
+    (tmp_path / "mod1" / "__manifest__.py").write_text("""{'name': 'mod1'}""")
+    mark_modules_uninstallable(tmp_path)
+    assert (tmp_path / "mod1" / "__manifest__.py").read_text() == (
+        """{'name': 'mod1',\n    'installable': False,\n}\n"""
+    )
+
+
+def test_mark_module_uninstallable_key_exists(tmp_path):
+    (tmp_path / "mod1").mkdir()
+    (tmp_path / "mod1" / "__manifest__.py").write_text(
+        """{'name': 'mod1', "installable": True}"""
+    )
+    mark_modules_uninstallable(tmp_path)
+    assert (tmp_path / "mod1" / "__manifest__.py").read_text() == (
+        """{'name': 'mod1', "installable": False}"""
+    )
+
+
+def test_mark_module_uninstallable_curly_braces(tmp_path):
+    assert mark_manifest_uninstallable(
+        textwrap.dedent(
+            """\
+            {
+                'name': 'mod1',
+                'external_dependencies': {
+                    'python': ['some_package'],
+                },
+                'license': 'AGPL-3',
+            }
+            """
+        )
+    ) == textwrap.dedent(
+        """\
+            {
+                'name': 'mod1',
+                'external_dependencies': {
+                    'python': ['some_package'],
+                },
+                'license': 'AGPL-3',
+                'installable': False,
+            }
+            """
+    )
diff --git a/tools/create_branch_from_previous.py b/tools/create_branch_from_previous.py
new file mode 100644
index 00000000..7ecb603a
--- /dev/null
+++ b/tools/create_branch_from_previous.py
@@ -0,0 +1,125 @@
+import subprocess
+from pathlib import Path
+
+import click
+
+from .manifest import mark_modules_uninstallable
+
+
+@click.command()
+@click.option("--odoo-version", required=True)
+@click.option("--new-branch-name")
+@click.option(
+    "--addons-dir",
+    type=click.Path(exists=True, file_okay=False, dir_okay=True, path_type=Path),
+    default=".",
+)
+@click.option(
+    "--data",
+    multiple=True,
+    help="Additional copier data, as key=value",
+)
+def main(
+    odoo_version: str,
+    new_branch_name: str | None,
+    addons_dir: Path,
+    data: list[str],
+) -> None:
+    """Create a new branch off an existing branch and set all addons installable=False.
+
+    To use it, go to a git clone of a repo and checkout the branch you want to start from.
+    """
+    if not new_branch_name:
+        new_branch_name = odoo_version
+    result = subprocess.run(
+        ["git", "rev-parse", "--abbrev-ref", "HEAD"],
+        check=True,
+        text=True,
+        capture_output=True,
+    )
+    previous_branch = result.stdout.strip()
+    subprocess.run(
+        [
+            "git",
+            "checkout",
+            "-b",
+            new_branch_name,
+        ],
+        check=True,
+    )
+    result = subprocess.run(
+        [
+            "copier",
+            "recopy",  # override local changes when creating a new branch
+            "--trust",
+            "--defaults",
+            "--overwrite",
+            f"--data=odoo_version={odoo_version}",
+            *(f"--data={d}" for d in data),
+        ],
+    )
+    if result.returncode != 0:
+        raise SystemExit("copier update failed, please fix manually")
+    result = subprocess.run(
+        [
+            "git",
+            "diff",
+            "--diff-filter=U",
+            "--quiet",
+        ],
+    )
+    if result.returncode != 0:
+        raise SystemExit(
+            "There are merge conflicts after copier update, please fix manually"
+        )
+    mark_modules_uninstallable(addons_dir)
+    if Path(".pre-commit-config.yaml").exists():
+        # First run pre-commit on .pre-commit-config.yaml, to exclude
+        # addons that are not installable.
+        subprocess.run(
+            [
+                "pre-commit",
+                "run",
+                "--files",
+                ".pre-commit-config.yaml",
+            ],
+            check=False,
+        )
+        # Run pre-commit once to let it apply auto fixes.
+        subprocess.run(
+            [
+                "pre-commit",
+                "run",
+                "--all-files",
+            ],
+            check=False,
+        )
+        # Run pre-commit a second time to check that everything is green.
+        result = subprocess.run(
+            [
+                "pre-commit",
+                "run",
+                "--all-files",
+            ],
+            check=False,
+        )
+        if result.returncode != 0:
+            raise SystemExit("pre-commit failed, please fix manually")
+    subprocess.run(
+        [
+            "git",
+            "add",
+            ".",
+        ],
+        check=True,
+    )
+    subprocess.run(
+        [
+            "git",
+            "commit",
+            "-m",
+            f"[MIG] Create {new_branch_name} from {previous_branch} "
+            f"for Odoo {odoo_version}",
+        ],
+        check=True,
+    )
diff --git a/tools/manifest.py b/tools/manifest.py
index daea0f36..5c1d4f30 100644
--- a/tools/manifest.py
+++ b/tools/manifest.py
@@ -3,6 +3,8 @@
 
 import ast
 import os
+import re
+from pathlib import Path
 
 MANIFEST_NAMES = ("__manifest__.py", "__openerp__.py", "__terp__.py")
 
@@ -41,3 +43,21 @@ def find_addons(addons_dir, installable_only=True):
         if installable_only and not manifest.get("installable", True):
             continue
         yield addon_name, addon_dir, manifest
+
+
+def mark_manifest_uninstallable(manifest_text: str) -> str:
+    manifest = ast.literal_eval(manifest_text)
+    if "installable" not in manifest:
+        src = r",?\s*}\s*$"
+        dest = ",\n    'installable': False,\n}\n"
+    else:
+        src = "[\"']installable[\"']: *True"
+        dest = '"installable": False'
+    return re.sub(src, dest, manifest_text, re.DOTALL)
+
+
+def mark_modules_uninstallable(addons_dir: Path) -> None:
+    for manifest_path in addons_dir.glob("*/__manifest__.py"):
+        manifest_text = manifest_path.read_text(encoding="utf-8")
+        new_manifest_text = mark_manifest_uninstallable(manifest_text)
+        manifest_path.write_text(new_manifest_text, encoding="utf-8")