diff --git a/recipes/README.recipes.md b/recipes/README.recipes.md
index 30731bcc5..3878f1568 100644
--- a/recipes/README.recipes.md
+++ b/recipes/README.recipes.md
@@ -383,7 +383,7 @@ Returns:
       https://gerrit-review.googlesource.com/Documentation/rest-api-changes.html#list-changes
 ### *recipe_modules* / [git](/recipes/recipe_modules/git)
 
-[DEPS](/recipes/recipe_modules/git/__init__.py#1): [infra\_paths](#recipe_modules-infra_paths), [recipe\_engine/context][recipe_engine/recipe_modules/context], [recipe\_engine/path][recipe_engine/recipe_modules/path], [recipe\_engine/platform][recipe_engine/recipe_modules/platform], [recipe\_engine/properties][recipe_engine/recipe_modules/properties], [recipe\_engine/python][recipe_engine/recipe_modules/python], [recipe\_engine/raw\_io][recipe_engine/recipe_modules/raw_io], [recipe\_engine/runtime][recipe_engine/recipe_modules/runtime], [recipe\_engine/step][recipe_engine/recipe_modules/step]
+[DEPS](/recipes/recipe_modules/git/__init__.py#1): [infra\_paths](#recipe_modules-infra_paths), [recipe\_engine/buildbucket][recipe_engine/recipe_modules/buildbucket], [recipe\_engine/context][recipe_engine/recipe_modules/context], [recipe\_engine/path][recipe_engine/recipe_modules/path], [recipe\_engine/platform][recipe_engine/recipe_modules/platform], [recipe\_engine/properties][recipe_engine/recipe_modules/properties], [recipe\_engine/python][recipe_engine/recipe_modules/python], [recipe\_engine/raw\_io][recipe_engine/recipe_modules/raw_io], [recipe\_engine/runtime][recipe_engine/recipe_modules/runtime], [recipe\_engine/step][recipe_engine/recipe_modules/step]
 
 #### **class [GitApi](/recipes/recipe_modules/git/api.py#10)([RecipeApi][recipe_engine/wkt/RecipeApi]):**
 
@@ -391,7 +391,7 @@ Returns:
 
 Return a git command step.
 
-— **def [bundle\_create](/recipes/recipe_modules/git/api.py#383)(self, bundle_path, rev_list_args=None, \*\*kwargs):**
+— **def [bundle\_create](/recipes/recipe_modules/git/api.py#382)(self, bundle_path, rev_list_args=None, \*\*kwargs):**
 
 Run 'git bundle create' on a Git repository.
 
@@ -444,7 +444,7 @@ Args:
 Returns: If the checkout was successful, this returns the commit hash of
   the checked-out-repo. Otherwise this returns None.
 
-— **def [config\_get](/recipes/recipe_modules/git/api.py#356)(self, prop_name, \*\*kwargs):**
+— **def [config\_get](/recipes/recipe_modules/git/api.py#355)(self, prop_name, \*\*kwargs):**
 
 Returns: (str) The Git config output, or None if no output was generated.
 
@@ -469,7 +469,7 @@ Returns:
 
 Fetches all tags from the remote.
 
-— **def [get\_remote\_url](/recipes/recipe_modules/git/api.py#373)(self, remote_name=None, \*\*kwargs):**
+— **def [get\_remote\_url](/recipes/recipe_modules/git/api.py#372)(self, remote_name=None, \*\*kwargs):**
 
 Returns: (str) The URL of the remote Git repository, or None.
 
@@ -477,11 +477,11 @@ Args:
   remote_name: (str) The name of the remote to query, defaults to 'origin'.
   kwargs: Forwarded to '__call__'.
 
-— **def [get\_timestamp](/recipes/recipe_modules/git/api.py#328)(self, commit='HEAD', test_data=None, \*\*kwargs):**
+— **def [get\_timestamp](/recipes/recipe_modules/git/api.py#327)(self, commit='HEAD', test_data=None, \*\*kwargs):**
 
 Find and return the timestamp of the given commit.
 
-— **def [new\_branch](/recipes/recipe_modules/git/api.py#396)(self, branch, name=None, upstream=None, \*\*kwargs):**
+— **def [new\_branch](/recipes/recipe_modules/git/api.py#395)(self, branch, name=None, upstream=None, \*\*kwargs):**
 
 Runs git new-branch on a Git repository, to be used before git cl upload.
 
@@ -491,7 +491,7 @@ Args:
   upstream (str): to origin/master.
   kwargs: Forwarded to '__call__'.
 
-— **def [rebase](/recipes/recipe_modules/git/api.py#337)(self, name_prefix, branch, dir_path, remote_name=None, \*\*kwargs):**
+— **def [rebase](/recipes/recipe_modules/git/api.py#336)(self, name_prefix, branch, dir_path, remote_name=None, \*\*kwargs):**
 
 Run rebase HEAD onto branch
 Args:
@@ -924,9 +924,9 @@ Raises:
 — **def [RunSteps](/recipes/recipe_modules/gerrit/examples/full.py#11)(api):**
 ### *recipes* / [git:examples/full](/recipes/recipe_modules/git/examples/full.py)
 
-[DEPS](/recipes/recipe_modules/git/examples/full.py#5): [git](#recipe_modules-git), [recipe\_engine/context][recipe_engine/recipe_modules/context], [recipe\_engine/path][recipe_engine/recipe_modules/path], [recipe\_engine/platform][recipe_engine/recipe_modules/platform], [recipe\_engine/properties][recipe_engine/recipe_modules/properties], [recipe\_engine/raw\_io][recipe_engine/recipe_modules/raw_io], [recipe\_engine/runtime][recipe_engine/recipe_modules/runtime], [recipe\_engine/step][recipe_engine/recipe_modules/step]
+[DEPS](/recipes/recipe_modules/git/examples/full.py#5): [git](#recipe_modules-git), [recipe\_engine/buildbucket][recipe_engine/recipe_modules/buildbucket], [recipe\_engine/context][recipe_engine/recipe_modules/context], [recipe\_engine/path][recipe_engine/recipe_modules/path], [recipe\_engine/platform][recipe_engine/recipe_modules/platform], [recipe\_engine/properties][recipe_engine/recipe_modules/properties], [recipe\_engine/raw\_io][recipe_engine/recipe_modules/raw_io], [recipe\_engine/runtime][recipe_engine/recipe_modules/runtime], [recipe\_engine/step][recipe_engine/recipe_modules/step]
 
-— **def [RunSteps](/recipes/recipe_modules/git/examples/full.py#18)(api):**
+— **def [RunSteps](/recipes/recipe_modules/git/examples/full.py#19)(api):**
 ### *recipes* / [git\_cl:examples/full](/recipes/recipe_modules/git_cl/examples/full.py)
 
 [DEPS](/recipes/recipe_modules/git_cl/examples/full.py#9): [git\_cl](#recipe_modules-git_cl), [recipe\_engine/path][recipe_engine/recipe_modules/path], [recipe\_engine/raw\_io][recipe_engine/recipe_modules/raw_io], [recipe\_engine/step][recipe_engine/recipe_modules/step]
diff --git a/recipes/recipe_modules/git/__init__.py b/recipes/recipe_modules/git/__init__.py
index f8faf3672..019c635d1 100644
--- a/recipes/recipe_modules/git/__init__.py
+++ b/recipes/recipe_modules/git/__init__.py
@@ -1,4 +1,5 @@
 DEPS = [
+  'recipe_engine/buildbucket',
   'recipe_engine/context',
   'recipe_engine/runtime',
   'recipe_engine/path',
diff --git a/recipes/recipe_modules/git/api.py b/recipes/recipe_modules/git/api.py
index 6b86546cc..2cdb0ec93 100644
--- a/recipes/recipe_modules/git/api.py
+++ b/recipes/recipe_modules/git/api.py
@@ -217,29 +217,28 @@ class GitApi(recipe_api.RecipeApi):
                can_fail_build=can_fail_build)
 
       # There are five kinds of refs we can be handed:
-      # 0) None. In this case, we default to properties['branch'].
-      # 1) A 40-character SHA1 hash.
-      # 2) A fully-qualifed arbitrary ref, e.g. 'refs/foo/bar/baz'.
-      # 3) A fully qualified branch name, e.g. 'refs/heads/master'.
-      #    Chop off 'refs/heads' and now it matches case (4).
+      # 0) None. In this case, we default to api.buildbucket.gitiles_commit.ref.
+      # 1) A fully qualified branch name, e.g. 'refs/heads/master'.
+      #    Chop off 'refs/heads/' and now it matches case (4).
+      # 2) A 40-character SHA1 hash.
+      # 3) A fully-qualifed arbitrary ref, e.g. 'refs/foo/bar/baz'.
       # 4) A branch name, e.g. 'master'.
       # Note that 'FETCH_HEAD' can be many things (and therefore not a valid
       # checkout target) if many refs are fetched, but we only explicitly fetch
       # one ref here, so this is safe.
+      if not ref:                                  # Case 0.
+        ref = self.m.buildbucket.gitiles_commit.ref or 'master'
+
+      # If it's a fully-qualified branch name, trim the 'refs/heads/' prefix.
+      if ref.startswith('refs/heads/'):            # Case 1.
+        ref = ref[len('refs/heads/'):]
+
       fetch_args = []
-      if not ref:                                  # Case 0
-        fetch_remote = remote_name
-        fetch_ref = self.m.properties.get('branch') or 'master'
-        checkout_ref = 'FETCH_HEAD'
-      elif self._GIT_HASH_RE.match(ref):        # Case 1.
+      if self._GIT_HASH_RE.match(ref):             # Case 2.
         fetch_remote = remote_name
         fetch_ref = ''
         checkout_ref = ref
-      elif ref.startswith('refs/heads/'):       # Case 3.
-        fetch_remote = remote_name
-        fetch_ref = ref[len('refs/heads/'):]
-        checkout_ref = 'FETCH_HEAD'
-      else:                                     # Cases 2 and 4.
+      else:                                        # Cases 3 and 4.
         fetch_remote = remote_name
         fetch_ref = ref
         checkout_ref = 'FETCH_HEAD'
diff --git a/recipes/recipe_modules/git/examples/full.py b/recipes/recipe_modules/git/examples/full.py
index 6461ef5bb..77321f017 100644
--- a/recipes/recipe_modules/git/examples/full.py
+++ b/recipes/recipe_modules/git/examples/full.py
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 DEPS = [
+  'recipe_engine/buildbucket',
   'recipe_engine/context',
   'recipe_engine/path',
   'recipe_engine/platform',
@@ -29,9 +30,11 @@ def RunSteps(api):
           True)
 
   # You can use api.git.checkout to perform all the steps of a safe checkout.
+  revision = (api.buildbucket.gitiles_commit.ref or
+              api.buildbucket.gitiles_commit.id)
   retVal = api.git.checkout(
       url,
-      ref=api.properties.get('revision'),
+      ref=revision,
       recursive=True,
       submodule_update_force=submodule_update_force,
       set_got_revision=api.properties.get('set_got_revision'),
@@ -84,7 +87,7 @@ def RunSteps(api):
 
   if api.properties.get('cat_file', None):
     step_result = api.git.cat_file_at_commit(api.properties['cat_file'],
-                                             api.properties['revision'],
+                                             revision,
                                              stdout=api.raw_io.output())
     if 'TestOutput' in step_result.stdout:
       pass  # Success!
@@ -101,18 +104,22 @@ def GenTests(api):
     api.runtime(is_luci=True, is_experimental=False)
   )
   yield api.test('basic_tags') + api.properties(tags=True)
-  yield api.test('basic_ref') + api.properties(revision='refs/foo/bar')
-  yield api.test('basic_branch') + api.properties(revision='refs/heads/testing')
-  yield api.test('basic_hash') + api.properties(
-      revision='abcdef0123456789abcdef0123456789abcdef01')
+  yield api.test('basic_ref') + api.buildbucket.ci_build(git_ref='refs/foo/bar')
+  yield api.test('basic_branch') + api.buildbucket.ci_build(
+      git_ref='refs/heads/testing')
+  yield api.test('basic_hash') + api.buildbucket.ci_build(
+      revision='abcdef0123456789abcdef0123456789abcdef01', git_ref=None)
   yield api.test('basic_file_name') + api.properties(checkout_file_name='DEPS')
   yield api.test('basic_submodule_update_force') + api.properties(
       submodule_update_force=True)
 
   yield api.test('platform_win') + api.platform.name('win')
 
-  yield api.test('curl_trace_file') + api.properties(
-      revision='refs/foo/bar', use_curl_trace=True)
+  yield (
+      api.test('curl_trace_file') +
+      api.properties(use_curl_trace=True) +
+      api.buildbucket.ci_build(git_ref='refs/foo/bar')
+  )
 
   yield (
     api.test('can_fail_build') +
@@ -160,7 +167,8 @@ def GenTests(api):
       api.test('cat-file_test') +
       api.step_data('git cat-file abcdef12345:TestFile',
                     stdout=api.raw_io.output('TestOutput')) +
-      api.properties(revision='abcdef12345', cat_file='TestFile'))
+      api.buildbucket.ci_build(revision='abcdef12345', git_ref=None) +
+      api.properties(cat_file='TestFile'))
 
   yield (
       api.test('git-cache-checkout') +