diff --git a/crates/project-model/src/build_scripts.rs b/crates/project-model/src/build_scripts.rs
index 38c1b37f0e3..f63a04ccdb9 100644
--- a/crates/project-model/src/build_scripts.rs
+++ b/crates/project-model/src/build_scripts.rs
@@ -428,8 +428,9 @@ pub(crate) fn rustc_crates(
             for p in rustc.packages() {
                 let package = &rustc[p];
                 if package.targets.iter().any(|&it| rustc[it].is_proc_macro) {
-                    if let Some((_, path)) =
-                        proc_macro_dylibs.iter().find(|(name, _)| *name == package.name)
+                    if let Some((_, path)) = proc_macro_dylibs
+                        .iter()
+                        .find(|(name, _)| *name.trim_start_matches("lib") == package.name)
                     {
                         bs.outputs[p].proc_macro_dylib_path = Some(path.clone());
                     }
diff --git a/crates/project-model/src/workspace.rs b/crates/project-model/src/workspace.rs
index faa6816fdc2..23c2f4b524b 100644
--- a/crates/project-model/src/workspace.rs
+++ b/crates/project-model/src/workspace.rs
@@ -932,7 +932,7 @@ fn cargo_to_crate_graph(
     if has_private {
         // If the user provided a path to rustc sources, we add all the rustc_private crates
         // and create dependencies on them for the crates which opt-in to that
-        if let Some((rustc_workspace, build_scripts)) = rustc {
+        if let Some((rustc_workspace, rustc_build_scripts)) = rustc {
             handle_rustc_crates(
                 &mut crate_graph,
                 &mut pkg_to_lib_crate,
@@ -945,7 +945,13 @@ fn cargo_to_crate_graph(
                 &pkg_crates,
                 &cfg_options,
                 override_cfg,
-                build_scripts,
+                if rustc_workspace.workspace_root() == cargo.workspace_root() {
+                    // the rustc workspace does not use the installed toolchain's proc-macro server
+                    // so we need to make sure we don't use the pre compiled proc-macros there either
+                    build_scripts
+                } else {
+                    rustc_build_scripts
+                },
                 target_layout,
             );
         }