diff --git a/build/fbcode_builder/getdeps.py b/build/fbcode_builder/getdeps.py
index f9ba16216..53396faf1 100755
--- a/build/fbcode_builder/getdeps.py
+++ b/build/fbcode_builder/getdeps.py
@@ -71,6 +71,23 @@ class ShowHostType(SubCmd):
 class ProjectCmdBase(SubCmd):
     def run(self, args):
         opts = setup_build_options(args)
+
+        if args.current_project is not None:
+            opts.repo_project = args.current_project
+        if args.project is None:
+            if opts.repo_project is None:
+                raise UsageError(
+                    "no project name specified, and no .projectid file found"
+                )
+            if opts.repo_project == "fbsource":
+                # The fbsource repository is a little special.  There is no project
+                # manifest file for it.  A specific project must always be explicitly
+                # specified when building from fbsource.
+                raise UsageError(
+                    "no project name specified (required when building in fbsource)"
+                )
+            args.project = opts.repo_project
+
         ctx_gen = opts.get_context_generator(facebook_internal=args.facebook_internal)
         if args.test_dependencies:
             ctx_gen.set_value_for_all_projects("test", "on")
@@ -101,6 +118,12 @@ class ProjectCmdBase(SubCmd):
 
             return project, os.path.abspath(path)
 
+        # If we are currently running from a project repository,
+        # use the current repository for the project sources.
+        build_opts = loader.build_opts
+        if build_opts.repo_project is not None and build_opts.repo_root is not None:
+            loader.set_project_src_dir(build_opts.repo_project, build_opts.repo_root)
+
         for arg in args.src_dir:
             project, path = parse_project_arg(arg, "--src-dir")
             loader.set_project_src_dir(project, path)
@@ -116,6 +139,7 @@ class ProjectCmdBase(SubCmd):
     def setup_parser(self, parser):
         parser.add_argument(
             "project",
+            nargs="?",
             help=(
                 "name of the project or path to a manifest "
                 "file describing the project"
@@ -133,6 +157,12 @@ class ProjectCmdBase(SubCmd):
             action="store_true",
             help="Enable building tests for dependencies as well.",
         )
+        parser.add_argument(
+            "--current-project",
+            help="Specify the name of the fbcode_builder manifest file for the "
+            "current repository.  If not specified, the code will attempt to find "
+            "this in a .projectid file in the repository root.",
+        )
         parser.add_argument(
             "--src-dir",
             default=[],
diff --git a/build/fbcode_builder/getdeps/buildopts.py b/build/fbcode_builder/getdeps/buildopts.py
index e730cd613..910361ce7 100644
--- a/build/fbcode_builder/getdeps/buildopts.py
+++ b/build/fbcode_builder/getdeps/buildopts.py
@@ -35,10 +35,28 @@ def containing_repo_type(path):
 
         parent = os.path.dirname(path)
         if parent == path:
-            return None
+            return None, None
         path = parent
 
 
+def detect_project(path):
+    repo_type, repo_root = containing_repo_type(path)
+    if repo_type is None:
+        return None, None
+
+    # Look for a .projectid file.  If it exists, read the project name from it.
+    project_id_path = os.path.join(repo_root, ".projectid")
+    try:
+        with open(project_id_path, "r") as f:
+            project_name = f.read().strip()
+            return repo_root, project_name
+    except EnvironmentError as ex:
+        if ex.errno != errno.ENOENT:
+            raise
+
+    return repo_root, None
+
+
 class BuildOptions(object):
     def __init__(
         self,
@@ -78,11 +96,13 @@ class BuildOptions(object):
                 self.project_hashes = hashes
                 break
 
-        # Use a simplistic heuristic to figure out if we're in fbsource
-        # and where the root of fbsource can be found
-        repo_type, repo_root = containing_repo_type(fbcode_builder_dir)
-        if repo_type == "hg":
-            self.fbsource_dir = repo_root
+        # Detect what repository and project we are being run from.
+        self.repo_root, self.repo_project = detect_project(os.getcwd())
+
+        # If we are running from an fbsource repository, set self.fbsource_dir
+        # to allow the ShipIt-based fetchers to use it.
+        if self.repo_project == "fbsource":
+            self.fbsource_dir = self.repo_root
         else:
             self.fbsource_dir = None