diff --git a/build_system/abi_cafe.rs b/build_system/abi_cafe.rs
index 5f20a377329..3f93c14a0fb 100644
--- a/build_system/abi_cafe.rs
+++ b/build_system/abi_cafe.rs
@@ -10,7 +10,7 @@ use super::SysrootKind;
 pub(crate) static ABI_CAFE_REPO: GitRepo =
     GitRepo::github("Gankra", "abi-cafe", "4c6dc8c9c687e2b3a760ff2176ce236872b37212", "abi-cafe");
 
-static ABI_CAFE: CargoProject = CargoProject::new(&ABI_CAFE_REPO.source_dir(), "abi_cafe");
+pub(crate) static ABI_CAFE: CargoProject = CargoProject::new(&ABI_CAFE_REPO.source_dir(), "abi_cafe");
 
 pub(crate) fn run(
     channel: &str,
diff --git a/build_system/build_backend.rs b/build_system/build_backend.rs
index 00d9a6ddea8..6ab39e48f21 100644
--- a/build_system/build_backend.rs
+++ b/build_system/build_backend.rs
@@ -5,7 +5,7 @@ use super::path::{Dirs, RelPath};
 use super::rustc_info::get_file_name;
 use super::utils::{is_ci, CargoProject, Compiler};
 
-static CG_CLIF: CargoProject = CargoProject::new(&RelPath::SOURCE, "cg_clif");
+pub(crate) static CG_CLIF: CargoProject = CargoProject::new(&RelPath::SOURCE, "cg_clif");
 
 pub(crate) fn build_backend(
     dirs: &Dirs,
diff --git a/build_system/build_sysroot.rs b/build_system/build_sysroot.rs
index 3ec00e08ef7..c7d80789f8a 100644
--- a/build_system/build_sysroot.rs
+++ b/build_system/build_sysroot.rs
@@ -153,7 +153,7 @@ pub(crate) static ORIG_BUILD_SYSROOT: RelPath = RelPath::SOURCE.join("build_sysr
 pub(crate) static BUILD_SYSROOT: RelPath = RelPath::DOWNLOAD.join("sysroot");
 pub(crate) static SYSROOT_RUSTC_VERSION: RelPath = BUILD_SYSROOT.join("rustc_version");
 pub(crate) static SYSROOT_SRC: RelPath = BUILD_SYSROOT.join("sysroot_src");
-static STANDARD_LIBRARY: CargoProject = CargoProject::new(&BUILD_SYSROOT, "build_sysroot");
+pub(crate) static STANDARD_LIBRARY: CargoProject = CargoProject::new(&BUILD_SYSROOT, "build_sysroot");
 
 fn build_clif_sysroot_for_triple(
     dirs: &Dirs,
diff --git a/build_system/prepare.rs b/build_system/prepare.rs
index c3faacd9244..4e898b30b7c 100644
--- a/build_system/prepare.rs
+++ b/build_system/prepare.rs
@@ -16,13 +16,22 @@ pub(crate) fn prepare(dirs: &Dirs) {
     }
     std::fs::create_dir_all(RelPath::DOWNLOAD.to_path(dirs)).unwrap();
 
+    spawn_and_wait(super::build_backend::CG_CLIF.fetch("cargo", dirs));
+
     prepare_sysroot(dirs);
+    spawn_and_wait(super::build_sysroot::STANDARD_LIBRARY.fetch("cargo", dirs));
+    spawn_and_wait(super::tests::LIBCORE_TESTS.fetch("cargo", dirs));
 
     super::abi_cafe::ABI_CAFE_REPO.fetch(dirs);
+    spawn_and_wait(super::abi_cafe::ABI_CAFE.fetch("cargo", dirs));
     super::tests::RAND_REPO.fetch(dirs);
+    spawn_and_wait(super::tests::RAND.fetch("cargo", dirs));
     super::tests::REGEX_REPO.fetch(dirs);
+    spawn_and_wait(super::tests::REGEX.fetch("cargo", dirs));
     super::tests::PORTABLE_SIMD_REPO.fetch(dirs);
+    spawn_and_wait(super::tests::PORTABLE_SIMD.fetch("cargo", dirs));
     super::bench::SIMPLE_RAYTRACER_REPO.fetch(dirs);
+    spawn_and_wait(super::bench::SIMPLE_RAYTRACER.fetch("cargo", dirs));
 }
 
 fn prepare_sysroot(dirs: &Dirs) {
diff --git a/build_system/tests.rs b/build_system/tests.rs
index 25c2457785e..4d638a4eced 100644
--- a/build_system/tests.rs
+++ b/build_system/tests.rs
@@ -97,12 +97,12 @@ const BASE_SYSROOT_SUITE: &[TestCase] = &[
 pub(crate) static RAND_REPO: GitRepo =
     GitRepo::github("rust-random", "rand", "0f933f9c7176e53b2a3c7952ded484e1783f0bf1", "rand");
 
-static RAND: CargoProject = CargoProject::new(&RAND_REPO.source_dir(), "rand");
+pub(crate) static RAND: CargoProject = CargoProject::new(&RAND_REPO.source_dir(), "rand");
 
 pub(crate) static REGEX_REPO: GitRepo =
     GitRepo::github("rust-lang", "regex", "341f207c1071f7290e3f228c710817c280c8dca1", "regex");
 
-static REGEX: CargoProject = CargoProject::new(&REGEX_REPO.source_dir(), "regex");
+pub(crate) static REGEX: CargoProject = CargoProject::new(&REGEX_REPO.source_dir(), "regex");
 
 pub(crate) static PORTABLE_SIMD_REPO: GitRepo = GitRepo::github(
     "rust-lang",
@@ -111,10 +111,10 @@ pub(crate) static PORTABLE_SIMD_REPO: GitRepo = GitRepo::github(
     "portable-simd",
 );
 
-static PORTABLE_SIMD: CargoProject =
+pub(crate) static PORTABLE_SIMD: CargoProject =
     CargoProject::new(&PORTABLE_SIMD_REPO.source_dir(), "portable_simd");
 
-static LIBCORE_TESTS: CargoProject =
+pub(crate) static LIBCORE_TESTS: CargoProject =
     CargoProject::new(&SYSROOT_SRC.join("library/core/tests"), "core_tests");
 
 const EXTENDED_SYSROOT_SUITE: &[TestCase] = &[