diff --git a/src/ci/docker/host-x86_64/optional-x86_64-gnu-parallel-frontend/Dockerfile b/src/ci/docker/host-x86_64/optional-x86_64-gnu-parallel-frontend/Dockerfile
index 8f7c7ebe35559..d8bfd6f52cb8b 100644
--- a/src/ci/docker/host-x86_64/optional-x86_64-gnu-parallel-frontend/Dockerfile
+++ b/src/ci/docker/host-x86_64/optional-x86_64-gnu-parallel-frontend/Dockerfile
@@ -24,13 +24,20 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
+ENV PARALLEL_FRONTEND_THREADS=4
+ENV ITERATION_COUNT=2
+
 ENV RUST_CONFIGURE_ARGS \
  --build=x86_64-unknown-linux-gnu \
  --enable-sanitizers \
  --enable-profiler \
  --enable-compiler-docs \
- --set llvm.libzstd=true
+ --set llvm.libzstd=true \
+ --set rust.parallel-frontend-threads=${PARALLEL_FRONTEND_THREADS}
 
 # Build the toolchain with multiple parallel frontend threads and then run tests
 # Tests are still compiled serially at the moment (intended to be changed in follow-ups).
-ENV SCRIPT python3 ../x.py --stage 2 test --set rust.parallel-frontend-threads=4
+# Running compiletest only tests for parallel frontend, then the rest without compiletest-only
+# options (i.e. `--parallel-frontend-threads=4 --iteration-count=2`)
+COPY ./scripts/optional-x86_64-gnu-parallel-frontend.sh /scripts/
+ENV SCRIPT="Must specify DOCKER_SCRIPT for this image"
diff --git a/src/ci/docker/scripts/optional-x86_64-gnu-parallel-frontend.sh b/src/ci/docker/scripts/optional-x86_64-gnu-parallel-frontend.sh
new file mode 100755
index 0000000000000..ed9aed263f25e
--- /dev/null
+++ b/src/ci/docker/scripts/optional-x86_64-gnu-parallel-frontend.sh
@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+
+set -eux -o pipefail
+
+if [ ! -v RUST_TEST_THREADS ]; then
+    RUST_TEST_THREADS_=$(python3 -c "print(max(1, $(nproc) // ${PARALLEL_FRONTEND_THREADS}))")
+else
+    RUST_TEST_THREADS_=${RUST_TEST_THREADS}
+fi
+
+RUST_TEST_THREADS=${RUST_TEST_THREADS_} \
+    python3 ../x.py --stage 2 test \
+    tests/ui \
+    -- \
+    --parallel-frontend-threads="${PARALLEL_FRONTEND_THREADS}" \
+    --iteration-count="${ITERATION_COUNT}"
diff --git a/src/ci/github-actions/jobs.yml b/src/ci/github-actions/jobs.yml
index 2bdf83a9c006b..834a8ddafb3d7 100644
--- a/src/ci/github-actions/jobs.yml
+++ b/src/ci/github-actions/jobs.yml
@@ -363,6 +363,8 @@ auto:
   - name: optional-x86_64-gnu-parallel-frontend
     # This test can be flaky, so do not cancel CI if it fails, for now.
     continue_on_error: true
+    env:
+      DOCKER_SCRIPT: optional-x86_64-gnu-parallel-frontend.sh
     <<: *job-linux-4c
 
   # This job ensures commits landing on nightly still pass the full