diff --git a/plugins/arcanist/README.md b/plugins/arcanist/README.md
index 9c15f09b5..f49e4344b 100644
--- a/plugins/arcanist/README.md
+++ b/plugins/arcanist/README.md
@@ -11,13 +11,14 @@ plugins=(... arcanist)
 ## Aliases
 
 | Alias   | Command                            |
-|---------|------------------------------------|
+| ------- | ---------------------------------- |
 | ara     | `arc amend`                        |
 | arb     | `arc branch`                       |
 | arco    | `arc cover`                        |
 | arci    | `arc commit`                       |
 | ard     | `arc diff`                         |
 | ardc    | `arc diff --create`                |
+| ardp    | `arc diff --preview`               |
 | ardnu   | `arc diff --nounit`                |
 | ardnupc | `arc diff --nounit --plan-changes` |
 | ardpc   | `arc diff --plan-changes`          |
@@ -27,3 +28,14 @@ plugins=(... arcanist)
 | arli    | `arc lint`                         |
 | arls    | `arc list`                         |
 | arpa    | `arc patch`                        |
+
+## Functions
+
+The following functions make copy pasting revision ids from the URL bar of your browser
+easier, as they allow for copy pasting the whole URL. For example: `ardu` accepts
+both `https://arcanist-url.com/<REVISION>` as well as `<REVISION>`.
+
+| Function                  | Command                           |
+| ------------------------- | --------------------------------- |
+| ardu [URL or revision_id] | `arc diff --update` [revision_id] |
+| arpa [URL or revision_id] | `arc patch` [revision_id]         |
diff --git a/plugins/arcanist/arcanist.plugin.zsh b/plugins/arcanist/arcanist.plugin.zsh
index 8918bffdd..88e6713e4 100644
--- a/plugins/arcanist/arcanist.plugin.zsh
+++ b/plugins/arcanist/arcanist.plugin.zsh
@@ -13,10 +13,25 @@ alias ardc='arc diff --create'
 alias ardnu='arc diff --nounit'
 alias ardnupc='arc diff --nounit --plan-changes'
 alias ardpc='arc diff --plan-changes'
+alias ardp='arc diff --preview' # creates a new diff in the phab interface
 
 alias are='arc export'
 alias arh='arc help'
 alias arl='arc land'
 alias arli='arc lint'
 alias arls='arc list'
-alias arpa='arc patch'
+
+#
+# Functions
+# (sorted alphabetically)
+#
+
+ardu() {
+  # Both `ardu https://arcanist-url.com/<REVISION>`, and `ardu <REVISION>` work.
+  arc diff --update "${1:t}"
+}
+
+arpa() {
+  # Both `arpa https://arcanist-url.com/<REVISION>`, and `arpa <REVISION>` work.
+  arc patch "${1:t}"
+}