diff --git a/.arcconfig b/.arcconfig
--- a/.arcconfig
+++ b/.arcconfig
@@ -1,4 +1,8 @@
 {
+  "phabricator.uri" : "https://reviews.llvm.org/",
   "repository.callsign" : "T",
-  "conduit_uri" : "https://reviews.llvm.org/"
+  "conduit_uri" : "https://reviews.llvm.org/",
+  "base": "git:HEAD^",
+  "arc.land.onto.default": "main",
+  "arc.land.onto": ["main"]
 }