diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-18/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-18/Dockerfile
index 487da5801522..7df32f18fdb3 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-18/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-18/Dockerfile
@@ -60,4 +60,5 @@ COPY host-x86_64/dist-x86_64-linux/build-gccjit.sh /scripts/
 RUN /scripts/build-gccjit.sh /scripts
 
 COPY scripts/x86_64-gnu-llvm.sh /tmp/script.sh
-ENV SCRIPT /tmp/script.sh
+ARG SCRIPT_ARG
+ENV SCRIPT="/tmp/script.sh && ${SCRIPT_ARG}"
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-19/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-19/Dockerfile
index 4991908fe773..2901daacd539 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-19/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-19/Dockerfile
@@ -60,4 +60,4 @@ COPY host-x86_64/dist-x86_64-linux/build-gccjit.sh /scripts/
 RUN /scripts/build-gccjit.sh /scripts
 
 COPY scripts/x86_64-gnu-llvm.sh /tmp/script.sh
-ENV SCRIPT /tmp/script.sh
+ENV SCRIPT="/tmp/script.sh && ${SCRIPT_ARG}"
diff --git a/src/ci/docker/scripts/x86_64-gnu-llvm.sh b/src/ci/docker/scripts/x86_64-gnu-llvm.sh
index dea38b6fd2a4..22ab93c37649 100755
--- a/src/ci/docker/scripts/x86_64-gnu-llvm.sh
+++ b/src/ci/docker/scripts/x86_64-gnu-llvm.sh
@@ -39,9 +39,6 @@ if [[ -z "${PR_CI_JOB}" ]]; then
         library/std library/alloc library/core
 fi
 
-# NOTE: intentionally uses all of `x.py`, `x`, and `x.ps1` to make sure they all work on Linux.
-../x.py --stage 2 test --skip src/tools/tidy
-
 # Run the `mir-opt` tests again but this time for a 32-bit target.
 # This enforces that tests using `// EMIT_MIR_FOR_EACH_BIT_WIDTH` have
 # both 32-bit and 64-bit outputs updated by the PR author, before
diff --git a/src/ci/github-actions/jobs.yml b/src/ci/github-actions/jobs.yml
index 959a9580e600..4ce2c6872e7b 100644
--- a/src/ci/github-actions/jobs.yml
+++ b/src/ci/github-actions/jobs.yml
@@ -117,6 +117,7 @@ pr:
       ENABLE_GCC_CODEGEN: "1"
       # We are adding (temporarily) a dummy commit on the compiler
       READ_ONLY_SRC: "0"
+      DOCKER_SCRIPT: python3 ../x.py --stage 2 test --skip src/tools/tidy
     <<: *job-linux-16c
   - image: x86_64-gnu-tools
     <<: *job-linux-16c
@@ -312,16 +313,41 @@ auto:
   - image: x86_64-gnu-distcheck
     <<: *job-linux-8c
 
-  - image: x86_64-gnu-llvm-19
+  # The x86_64-gnu-llvm-19 job is split into multiple jobs to run tests in parallel.
+  # x86_64-gnu-llvm-19-1 skips tests that run in x86_64-gnu-llvm-19-2.
+  - image: x86_64-gnu-llvm-19-1
     env:
       RUST_BACKTRACE: 1
-    <<: *job-linux-8c
+      IMAGE: x86_64-gnu-llvm-19
+      <<: *stage_2_test_set1
+    <<: *job-linux-4c
 
-  - image: x86_64-gnu-llvm-18
+  # Skip tests that run in x86_64-gnu-llvm-19-2
+  - image: x86_64-gnu-llvm-19-2
+    env:
+      RUST_BACKTRACE: 1
+      IMAGE: x86_64-gnu-llvm-19
+      <<: *stage_2_test_set2
+    <<: *job-linux-4c
+
+  # The x86_64-gnu-llvm-18 job is split into multiple jobs to run tests in parallel.
+  # x86_64-gnu-llvm-18-1 skips tests that run in x86_64-gnu-llvm-18-2.
+  - image: x86_64-gnu-llvm-18-1
     env:
       RUST_BACKTRACE: 1
       READ_ONLY_SRC: "0"
-    <<: *job-linux-8c
+      IMAGE: x86_64-gnu-llvm-18
+      <<: *stage_2_test_set1
+    <<: *job-linux-4c
+
+  # Skip tests that run in x86_64-gnu-llvm-18-2
+  - image: x86_64-gnu-llvm-18-2
+    env:
+      RUST_BACKTRACE: 1
+      READ_ONLY_SRC: "0"
+      IMAGE: x86_64-gnu-llvm-18
+      <<: *stage_2_test_set2
+    <<: *job-linux-4c
 
   - image: x86_64-gnu-nopt
     <<: *job-linux-4c