diff --git a/build/fbcode_builder/getdeps.py b/build/fbcode_builder/getdeps.py
index 5953338b0..74a553288 100755
--- a/build/fbcode_builder/getdeps.py
+++ b/build/fbcode_builder/getdeps.py
@@ -213,7 +213,7 @@ class BuildCmd(SubCmd):
 
         manifest = load_project(opts, args.project)
 
-        ctx = context_from_host_tuple()
+        ctx = context_from_host_tuple(facebook_internal=args.facebook_internal)
         print("Building on %s" % ctx)
         projects = manifests_in_dependency_order(opts, manifest, ctx)
         manifests_by_name = {m.name: m for m in projects}
@@ -313,7 +313,7 @@ class TestCmd(SubCmd):
         opts = setup_build_options(args)
         manifest = load_project(opts, args.project)
 
-        ctx = context_from_host_tuple()
+        ctx = context_from_host_tuple(facebook_internal=args.facebook_internal)
         ctx["test"] = "on"
         projects = manifests_in_dependency_order(opts, manifest, ctx)
         manifests_by_name = {m.name: m for m in projects}
@@ -388,6 +388,12 @@ def build_argparser():
         action="store_true",
         default=False,
     )
+    common_args.add_argument(
+        "--facebook-internal",
+        help="Setup the build context as an FB internal build",
+        action="store_true",
+        default=False,
+    )
 
     ap = argparse.ArgumentParser(
         description="Get and build dependencies and projects", parents=[common_args]
diff --git a/build/fbcode_builder/getdeps/platform.py b/build/fbcode_builder/getdeps/platform.py
index c52bc0fc6..d3368c2c4 100644
--- a/build/fbcode_builder/getdeps/platform.py
+++ b/build/fbcode_builder/getdeps/platform.py
@@ -98,7 +98,7 @@ class HostType(object):
         )
 
 
-def context_from_host_tuple(host_tuple=None):
+def context_from_host_tuple(host_tuple=None, facebook_internal=False):
     """ Given an optional host tuple, construct a context appropriate
     for passing to the boolean expression evaluator so that conditional
     sections in manifests can be resolved. """
@@ -113,4 +113,5 @@ def context_from_host_tuple(host_tuple=None):
         "os": host_type.ostype,
         "distro": host_type.distro,
         "distro_vers": host_type.distrovers,
+        "fb": "on" if facebook_internal else "off",
     }
diff --git a/build/fbcode_builder/manifests/watchman b/build/fbcode_builder/manifests/watchman
index 81e3d6559..5405331be 100644
--- a/build/fbcode_builder/manifests/watchman
+++ b/build/fbcode_builder/manifests/watchman
@@ -26,3 +26,10 @@ fbcode/eden/fs/service = eden/fs/service
 
 [cmake.defines]
 ENABLE_EDEN_SUPPORT=ON
+
+# FB macos specific settings
+[cmake.defines.all(fb=on,os=darwin)]
+# this path is coupled with the FB internal watchman-osx.spec
+WATCHMAN_STATE_DIR=/opt/facebook/watchman/var/run/watchman
+# tell cmake not to try to create /opt/facebook/...
+INSTALL_WATCHMAN_STATE_DIR=OFF