diff --git a/Cargo.lock b/Cargo.lock
index 00cfe8e..25c210b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -276,6 +276,7 @@ dependencies = [
  "directories",
  "serde",
  "toml",
+ "urlencoding",
  "which",
 ]
 
@@ -405,6 +406,12 @@ version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5a5f39404a5da50712a4c1eecf25e90dd62b613502b7e925fd4e4d19b5c96512"
 
+[[package]]
+name = "urlencoding"
+version = "2.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "daf8dba3b7eb870caf1ddeed7bc9d2a049f3cfdfae7cb521b087cc33ae4c49da"
+
 [[package]]
 name = "utf8parse"
 version = "0.2.2"
diff --git a/Cargo.toml b/Cargo.toml
index e5bda87..4b11d4d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,6 +13,7 @@ clap = { version = "4", features = ["derive"] }
 directories = "6"
 toml = "0.8"
 serde = { version = "1", features = ["derive"] }
+urlencoding = "2"
 which = "8"
 
 [profile.release]
diff --git a/src/bin/rustc_josh_sync.rs b/src/bin/rustc_josh_sync.rs
index 22818dd..ef8c3d5 100644
--- a/src/bin/rustc_josh_sync.rs
+++ b/src/bin/rustc_josh_sync.rs
@@ -4,7 +4,7 @@ use rustc_josh_sync::SyncContext;
 use rustc_josh_sync::config::{JoshConfig, load_config};
 use rustc_josh_sync::josh::{JoshProxy, try_install_josh};
 use rustc_josh_sync::sync::{GitSync, RustcPullError, UPSTREAM_REPO};
-use rustc_josh_sync::utils::prompt;
+use rustc_josh_sync::utils::{get_current_head_sha, prompt};
 use std::path::{Path, PathBuf};
 
 const DEFAULT_CONFIG_PATH: &str = "josh-sync.toml";
@@ -109,10 +109,24 @@ fn main() -> anyhow::Result<()> {
                 .context("cannot perform push")?;
 
             // Open PR with `subtree update` title to silence the `no-merges` triagebot check
+            let title = format!("{} subtree update", ctx.config.repo);
+            let head = get_current_head_sha()?;
+
+            let merge_msg = format!(
+                r#"Subtree update of `{repo}` to https://github.com/{full_repo}/commit/{head}.
+
+Created using https://github.com/rust-lang/josh-sync.
+
+r? @ghost"#,
+                repo = ctx.config.repo,
+                full_repo = ctx.config.full_repo_name(),
+            );
+
             println!(
                 r#"You can create the rustc PR using the following URL:
-https://github.com/{UPSTREAM_REPO}/compare/{username}:{branch}?quick_pull=1&title={}+subtree+update&body=r?+@ghost"#,
-                ctx.config.repo
+https://github.com/{UPSTREAM_REPO}/compare/{username}:{branch}?quick_pull=1&title={}&body={}"#,
+                urlencoding::encode(&title),
+                urlencoding::encode(&merge_msg)
             );
         }
     }
diff --git a/src/sync.rs b/src/sync.rs
index aaa949c..d5afcb6 100644
--- a/src/sync.rs
+++ b/src/sync.rs
@@ -1,7 +1,7 @@
 use crate::SyncContext;
 use crate::josh::JoshProxy;
-use crate::utils::run_command_at;
 use crate::utils::{ensure_clean_git_state, prompt};
+use crate::utils::{get_current_head_sha, run_command_at};
 use crate::utils::{run_command, stream_command};
 use anyhow::{Context, Error};
 use std::path::{Path, PathBuf};
@@ -64,7 +64,7 @@ impl GitSync {
             &self.context.config.construct_josh_filter(),
         );
 
-        let orig_head = run_command(["git", "rev-parse", "HEAD"])?;
+        let orig_head = get_current_head_sha()?;
         println!(
             "previous upstream base: {:?}",
             self.context.last_upstream_sha
@@ -137,8 +137,7 @@ This updates the rust-version file to {upstream_sha}."#,
         };
         let num_roots_before = num_roots()?;
 
-        let sha =
-            run_command(&["git", "rev-parse", "HEAD"]).context("failed to get current commit")?;
+        let sha = get_current_head_sha()?;
 
         // The filtered SHA of upstream
         let incoming_ref = run_command(["git", "rev-parse", "FETCH_HEAD"])?;
@@ -170,8 +169,7 @@ This merge was created using https://github.com/rust-lang/josh-sync.
         ])
         .context("FAILED to merge new commits, something went wrong")?;
 
-        let current_sha =
-            run_command(&["git", "rev-parse", "HEAD"]).context("FAILED to get current commit")?;
+        let current_sha = get_current_head_sha()?;
         if current_sha == sha {
             eprintln!(
                 "No merge was performed, no changes to pull were found. Rolling back the preparation commit."
@@ -261,7 +259,7 @@ This merge was created using https://github.com/rust-lang/josh-sync.
             &["git", "fetch", &josh_url, &branch],
             &std::env::current_dir().unwrap(),
         )?;
-        let head = run_command(&["git", "rev-parse", "HEAD"])?;
+        let head = get_current_head_sha()?;
         let fetch_head = run_command(&["git", "rev-parse", "FETCH_HEAD"])?;
         if head != fetch_head {
             return Err(anyhow::anyhow!(
diff --git a/src/utils.rs b/src/utils.rs
index fb23724..dd9d2aa 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -1,3 +1,4 @@
+use anyhow::Context;
 use std::path::Path;
 use std::process::Command;
 
@@ -67,6 +68,10 @@ pub fn ensure_clean_git_state() {
     assert!(read.is_empty(), "working directory must be clean");
 }
 
+pub fn get_current_head_sha() -> anyhow::Result<String> {
+    run_command(&["git", "rev-parse", "HEAD"]).context("failed to get current commit")
+}
+
 /// Ask a prompt to user and return true if they responded with `y`.
 /// Returns `default_response` on CI.
 pub fn prompt(prompt: &str, default_response: bool) -> bool {