diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 8f076ad914d..3a256bb50f2 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -301,7 +301,9 @@ pub struct Build {
     ar: HashMap<TargetSelection, PathBuf>,
     ranlib: HashMap<TargetSelection, PathBuf>,
     // Miscellaneous
+    // allow bidirectional lookups: both name -> path and path -> name
     crates: HashMap<Interned<String>, Crate>,
+    crate_paths: HashMap<PathBuf, Interned<String>>,
     is_sudo: bool,
     ci_env: CiEnv,
     delayed_failures: RefCell<Vec<String>>,
@@ -491,6 +493,7 @@ impl Build {
             ar: HashMap::new(),
             ranlib: HashMap::new(),
             crates: HashMap::new(),
+            crate_paths: HashMap::new(),
             is_sudo,
             ci_env: CiEnv::current(),
             delayed_failures: RefCell::new(Vec::new()),
diff --git a/src/bootstrap/metadata.rs b/src/bootstrap/metadata.rs
index 59dc50be47f..e193e70a0c4 100644
--- a/src/bootstrap/metadata.rs
+++ b/src/bootstrap/metadata.rs
@@ -49,7 +49,11 @@ pub fn build(build: &mut Build) {
                 .filter(|dep| dep.source.is_none())
                 .map(|dep| INTERNER.intern_string(dep.name))
                 .collect();
-            build.crates.insert(name, Crate { name, deps, path });
+            let krate = Crate { name, deps, path };
+            let relative_path = krate.local_path(build);
+            build.crates.insert(name, krate);
+            let existing_path = build.crate_paths.insert(relative_path, name);
+            assert!(existing_path.is_none(), "multiple crates with the same path");
         }
     }
 }
diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index c8b76809aba..83561ffdb36 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -21,7 +21,6 @@ use crate::native;
 use crate::tool::{self, SourceType, Tool};
 use crate::toolstate::ToolState;
 use crate::util::{self, add_link_lib_path, dylib_path, dylib_path_var, output, t};
-use crate::Crate as CargoCrate;
 use crate::{envify, CLang, DocTests, GitRepo, Mode};
 
 const ADB_TEST_DIR: &str = "/data/tmp/work";
@@ -1901,19 +1900,10 @@ impl Step for CrateLibrustc {
     fn make_run(run: RunConfig<'_>) {
         let builder = run.builder;
         let compiler = builder.compiler(builder.top_stage, run.build_triple());
+        let krate = builder.crate_paths[&run.path];
+        let test_kind = builder.kind.into();
 
-        for krate in builder.in_tree_crates("rustc-main", Some(run.target)) {
-            if krate.path.ends_with(&run.path) {
-                let test_kind = builder.kind.into();
-
-                builder.ensure(CrateLibrustc {
-                    compiler,
-                    target: run.target,
-                    test_kind,
-                    krate: krate.name,
-                });
-            }
-        }
+        builder.ensure(CrateLibrustc { compiler, target: run.target, test_kind, krate });
     }
 
     fn run(self, builder: &Builder<'_>) {
@@ -1947,24 +1937,10 @@ impl Step for Crate {
     fn make_run(run: RunConfig<'_>) {
         let builder = run.builder;
         let compiler = builder.compiler(builder.top_stage, run.build_triple());
+        let test_kind = builder.kind.into();
+        let krate = builder.crate_paths[&run.path];
 
-        let make = |mode: Mode, krate: &CargoCrate| {
-            let test_kind = builder.kind.into();
-
-            builder.ensure(Crate {
-                compiler,
-                target: run.target,
-                mode,
-                test_kind,
-                krate: krate.name,
-            });
-        };
-
-        for krate in builder.in_tree_crates("test", Some(run.target)) {
-            if krate.path.ends_with(&run.path) {
-                make(Mode::Std, krate);
-            }
-        }
+        builder.ensure(Crate { compiler, target: run.target, mode: Mode::Std, test_kind, krate });
     }
 
     /// Runs all unit tests plus documentation tests for a given crate defined