diff --git a/src/tools/compiletest/src/header.rs b/src/tools/compiletest/src/header.rs
index caae87393ff9a..63d05886166ae 100644
--- a/src/tools/compiletest/src/header.rs
+++ b/src/tools/compiletest/src/header.rs
@@ -35,9 +35,10 @@ impl HeadersCache {
 /// the test.
 #[derive(Default)]
 pub struct EarlyProps {
-    pub aux: Vec<String>,
-    pub aux_bin: Vec<String>,
-    pub aux_crate: Vec<(String, String)>,
+    /// Auxiliary crates that should be built and made available to this test.
+    /// Included in [`EarlyProps`] so that the indicated files can participate
+    /// in up-to-date checking. Building happens via [`TestProps::aux`] instead.
+    pub(crate) aux: AuxProps,
     pub revisions: Vec<String>,
 }
 
@@ -57,21 +58,7 @@ impl EarlyProps {
             testfile,
             rdr,
             &mut |HeaderLine { directive: ln, .. }| {
-                config.push_name_value_directive(ln, directives::AUX_BUILD, &mut props.aux, |r| {
-                    r.trim().to_string()
-                });
-                config.push_name_value_directive(
-                    ln,
-                    directives::AUX_BIN,
-                    &mut props.aux_bin,
-                    |r| r.trim().to_string(),
-                );
-                config.push_name_value_directive(
-                    ln,
-                    directives::AUX_CRATE,
-                    &mut props.aux_crate,
-                    Config::parse_aux_crate,
-                );
+                parse_and_update_aux(config, ln, &mut props.aux);
                 config.parse_and_update_revisions(ln, &mut props.revisions);
             },
         );
@@ -920,14 +907,6 @@ fn iter_header(
 }
 
 impl Config {
-    fn parse_aux_crate(r: String) -> (String, String) {
-        let mut parts = r.trim().splitn(2, '=');
-        (
-            parts.next().expect("missing aux-crate name (e.g. log=log.rs)").to_string(),
-            parts.next().expect("missing aux-crate value (e.g. log=log.rs)").to_string(),
-        )
-    }
-
     fn parse_and_update_revisions(&self, line: &str, existing: &mut Vec<String>) {
         if let Some(raw) = self.parse_name_value_directive(line, "revisions") {
             let mut duplicates: HashSet<_> = existing.iter().cloned().collect();
diff --git a/src/tools/compiletest/src/header/tests.rs b/src/tools/compiletest/src/header/tests.rs
index 10ec2a1806f8d..22dfa349e2bc3 100644
--- a/src/tools/compiletest/src/header/tests.rs
+++ b/src/tools/compiletest/src/header/tests.rs
@@ -242,7 +242,8 @@ fn aux_build() {
         //@ aux-build: b.rs
         "
         )
-        .aux,
+        .aux
+        .builds,
         vec!["a.rs", "b.rs"],
     );
 }
diff --git a/src/tools/compiletest/src/lib.rs b/src/tools/compiletest/src/lib.rs
index 98375a21b04b9..30215c0bbe68d 100644
--- a/src/tools/compiletest/src/lib.rs
+++ b/src/tools/compiletest/src/lib.rs
@@ -862,7 +862,8 @@ fn files_related_to_test(
         related.push(testpaths.file.clone());
     }
 
-    for aux in &props.aux {
+    for aux in &props.aux.builds {
+        // FIXME(Zalathar): Perform all `auxiliary` path resolution in one place.
         let path = testpaths.file.parent().unwrap().join("auxiliary").join(aux);
         related.push(path);
     }