diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/config.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/config.rs
index 1bc164b157a7..90857a307310 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/config.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/config.rs
@@ -1070,6 +1070,7 @@ struct ClientInfo {
     version: Option<Version>,
 }
 
+/// The configuration of this rust-analyzer instance.
 #[derive(Clone)]
 pub struct Config {
     /// Projects that have a Cargo.toml or a rust-project.json in a
@@ -1079,11 +1080,16 @@ pub struct Config {
     /// Projects whose configuration was generated by a command
     /// configured in discoverConfig.
     discovered_projects_from_command: Vec<ProjectJsonFromCommand>,
-    /// The workspace roots as registered by the LSP client
+    /// The workspace roots as registered by the LSP client.
     workspace_roots: Vec<AbsPathBuf>,
     caps: ClientCapabilities,
-    /// The LSP root path, deprecated in favor of `workspace_roots`
+
+    /// The root of the first project encountered. This is deprecated
+    /// because rust-analyzer might be handling multiple projects.
+    ///
+    /// Prefer `workspace_roots` and `workspace_root_for()`.
     root_path: AbsPathBuf,
+
     snippets: Vec<Snippet>,
     client_info: Option<ClientInfo>,
 
@@ -1787,9 +1793,23 @@ fn sort_objects_by_field(json: &mut serde_json::Value) {
         s
     }
 
-    pub fn root_path(&self) -> &AbsPathBuf {
-        // We should probably use `workspace_roots` here if set
-        &self.root_path
+    /// Find the workspace root that contains the given path, using the
+    /// longest prefix match.
+    pub fn workspace_root_for(&self, path: &AbsPath) -> &AbsPathBuf {
+        self.workspace_roots
+            .iter()
+            .filter(|root| path.starts_with(root.as_path()))
+            .max_by_key(|root| root.as_str().len())
+            .unwrap_or(self.default_root_path())
+    }
+
+    /// Best-effort root path for the current project.
+    ///
+    /// Use `workspace_root_for` where possible, because
+    /// `default_root_path` may return the wrong path when a user has
+    /// multiple workspaces.
+    pub fn default_root_path(&self) -> &AbsPathBuf {
+        self.workspace_roots.first().unwrap_or(&self.root_path)
     }
 
     pub fn caps(&self) -> &ClientCapabilities {
diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/handlers/request.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/handlers/request.rs
index c24591b7ab75..9c2e0a5f321b 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/handlers/request.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/handlers/request.rs
@@ -2453,7 +2453,14 @@ fn run_rustfmt(
                     let cmd_path = if command.contains(std::path::MAIN_SEPARATOR)
                         || (cfg!(windows) && command.contains('/'))
                     {
-                        snap.config.root_path().join(cmd).into()
+                        let project_root = Utf8PathBuf::from_path_buf(current_dir.clone())
+                            .ok()
+                            .and_then(|p| AbsPathBuf::try_from(p).ok());
+                        let project_root = project_root
+                            .as_ref()
+                            .map(|dir| snap.config.workspace_root_for(dir))
+                            .unwrap_or(snap.config.default_root_path());
+                        project_root.join(cmd).into()
                     } else {
                         cmd
                     };
diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/main_loop.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/main_loop.rs
index 7c494de6f73d..a8c3d062d041 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/main_loop.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/main_loop.rs
@@ -830,12 +830,19 @@ fn handle_task(&mut self, prime_caches_progress: &mut Vec<PrimeCachesProgress>,
                     let command = cfg.command.clone();
                     let discover = DiscoverCommand::new(self.discover_sender.clone(), command);
 
+                    let discover_path = match &arg {
+                        DiscoverProjectParam::Buildfile(it) => it,
+                        DiscoverProjectParam::Path(it) => it,
+                    };
+                    let current_dir =
+                        self.config.workspace_root_for(discover_path.as_path()).clone();
+
                     let arg = match arg {
                         DiscoverProjectParam::Buildfile(it) => DiscoverArgument::Buildfile(it),
                         DiscoverProjectParam::Path(it) => DiscoverArgument::Path(it),
                     };
 
-                    match discover.spawn(arg, self.config.root_path().as_ref()) {
+                    match discover.spawn(arg, current_dir.as_ref()) {
                         Ok(handle) => {
                             if self.discover_jobs_active == 0 {
                                 let title = &cfg.progress_label.clone();
@@ -953,7 +960,7 @@ fn handle_vfs_msg(
                 if let Some(dir) = dir {
                     message += &format!(
                         ": {}",
-                        match dir.strip_prefix(self.config.root_path()) {
+                        match dir.strip_prefix(self.config.workspace_root_for(&dir)) {
                             Some(relative_path) => relative_path.as_utf8_path(),
                             None => dir.as_ref(),
                         }
diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/reload.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/reload.rs
index 83f4a19b39fa..71accbed4ef1 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/reload.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/reload.rs
@@ -390,7 +390,7 @@ pub(crate) fn fetch_build_data(&mut self, cause: Cause) {
         info!(%cause, "will fetch build data");
         let workspaces = Arc::clone(&self.workspaces);
         let config = self.config.cargo(None);
-        let root_path = self.config.root_path().clone();
+        let root_path = self.config.default_root_path().clone();
 
         self.task_pool.handle.spawn_with_sender(ThreadIntent::Worker, move |sender| {
             sender.send(Task::FetchBuildData(BuildDataProgress::Begin)).unwrap();
@@ -883,7 +883,7 @@ fn reload_flycheck(&mut self) {
                     config,
                     crate::flycheck::FlycheckConfigJson::default(),
                     None,
-                    self.config.root_path().clone(),
+                    self.config.default_root_path().clone(),
                     None,
                     None,
                 )]