diff --git a/.oniro-ci/machines-and-flavours.yaml b/.oniro-ci/machines-and-flavours.yaml
index 3f544b5c2f54617ece6d3913f8195e40637d379e..c1bacf9ddf84db12be156525df2d5a34efaf7373 100644
--- a/.oniro-ci/machines-and-flavours.yaml
+++ b/.oniro-ci/machines-and-flavours.yaml
@@ -20,6 +20,12 @@ linux-qemu-x86:
     # tainted build intermediate files, downloads or published artifacts.
     CI_ONIRO_BB_LOCAL_CONF_BB_GENERATE_MIRROR_TARBALLS: 1
     CI_ONIRO_JOB_ARTIFACTS: "*.wic.* *.bmap ovmf.qcow2"
+  parallel:
+    matrix:
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "clang"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "llvm"
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "gcc"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "gnu"
 
 linux-qemu-x86_64:
   extends: .build-wic-image
@@ -31,14 +37,32 @@ linux-qemu-x86_64:
     CI_ONIRO_BUILD_CACHE: "pub"
     CI_ONIRO_BB_LOCAL_CONF_BB_GENERATE_MIRROR_TARBALLS: 1
     CI_ONIRO_JOB_ARTIFACTS: "*.wic.* *.bmap ovmf.qcow2"
+  parallel:
+    matrix:
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "clang"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "llvm"
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "gcc"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "gnu"
 
 linux-seco-intel-b68:
   extends: .build-wic-image
   variables:
+    MACHINE: seco-intel-b68
     CI_ONIRO_BUILD_FLAVOUR: linux
     CI_ONIRO_RECIPE_NAME: oniro-image-base-tests
+
+linux-seco-intel-b68:
+  extends: .build-wic-image
+  variables:
     MACHINE: seco-intel-b68
+    CI_ONIRO_BUILD_FLAVOUR: linux
+    CI_ONIRO_RECIPE_NAME: oniro-image-base-tests
+    CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "clang"
+    CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "llvm"
+  when: manual
+  allow_failure: true
 
+    
 linux-seco-intel-b68-extra:
   extends: .build-linux
   variables:
@@ -64,6 +88,17 @@ linux-seco-imx8mm-c61-4gb:
     # See build-generic.yaml for explanation of CI_ONIRO_BB_LOCAL_CONF_ variables.
     CI_ONIRO_BB_LOCAL_CONF_ACCEPT_FSL_EULA: 1
     CI_ONIRO_JOB_ARTIFACTS: "*.wic.* *.bmap flash.bin-seco-imx8mm-c61*"
+  parallel:
+    matrix:
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "clang"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "llvm"
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "gcc"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "gnu"
+  rules:
+    - if: '$CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN == "clang"'
+      allow_failure: true
+      when: manual
+    - when: on_success
 
 linux-seco-imx8mm-c61-4gb-extra:
   extends: .build-linux
@@ -82,6 +117,20 @@ linux-raspberrypi4-64:
     CI_ONIRO_BUILD_FLAVOUR: linux
     CI_ONIRO_RECIPE_NAME: oniro-image-base-tests
 
+## We don't use matrix job here because clang build has to be fixed
+## setting rules in matrix job causes broken dependencies
+## see: https://gitlab.eclipse.org/eclipse/oniro-core/oniro/-/issues/574
+linux-raspberrypi4-64-clang:
+  extends: .build-wic-image
+  variables:
+    MACHINE: raspberrypi4-64
+    CI_ONIRO_BUILD_FLAVOUR: linux
+    CI_ONIRO_RECIPE_NAME: oniro-image-base-tests
+    CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "clang"
+    CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "llvm"
+  when: manual
+  allow_failure: true
+
 zephyr-qemu-x86:
   extends: .build-zephyr-image
   variables:
@@ -92,6 +141,17 @@ zephyr-qemu-x86:
     CI_ONIRO_RECIPE_NAME: zephyr-philosophers
     CI_ONIRO_BUILD_FLAVOUR: zephyr
     CI_ONIRO_INSTANCE_SIZE: s3.large.2
+  parallel:
+    matrix:
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "clang"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "llvm"
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "gcc"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "gnu"
+  rules:
+    - if: '$CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN == "clang"'
+      allow_failure: true
+      when: manual
+    - when: on_success
 
 zephyr-qemu-cortex-m3:
   extends: .build-zephyr-image
@@ -103,6 +163,17 @@ zephyr-qemu-cortex-m3:
     CI_ONIRO_RECIPE_NAME: zephyr-philosophers
     CI_ONIRO_BUILD_FLAVOUR: zephyr
     CI_ONIRO_INSTANCE_SIZE: s3.large.2
+  parallel:
+    matrix:
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "clang"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "llvm"
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "gcc"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "gnu"
+  rules:
+    - if: '$CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN == "clang"'
+      allow_failure: true
+      when: manual
+    - when: on_success
 
 zephyr-96b-nitrogen:
   extends: .build-zephyr-image
@@ -111,6 +182,17 @@ zephyr-96b-nitrogen:
     CI_ONIRO_RECIPE_NAME: zephyr-philosophers
     CI_ONIRO_BUILD_FLAVOUR: zephyr
     CI_ONIRO_INSTANCE_SIZE: s3.large.2
+  parallel:
+    matrix:
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "clang"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "llvm"
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "gcc"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "gnu"
+  rules:
+    - if: '$CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN == "clang"'
+      allow_failure: true
+      when: manual
+    - when: on_success
 
 zephyr-96b-nitrogen-tests:
   extends: .build-zephyr-image
@@ -138,11 +220,35 @@ zephyr-nrf52840dk-nrf52840:
   extends: .build-zephyr
   variables:
     MACHINE: nrf52840dk-nrf52840
+  parallel:
+    matrix:
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "clang"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "llvm"
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "gcc"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "gnu"
+  rules:
+    - if: '$CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN == "clang"'
+      allow_failure: true
+      when: manual
+    - when: on_success
+
 
 zephyr-arduino-nano-33-ble:
   extends: .build-zephyr
   variables:
     MACHINE: arduino-nano-33-ble
+  parallel:
+    matrix:
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "clang"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "llvm"
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "gcc"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "gnu"
+  rules:
+    - if: '$CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN == "clang"'
+      allow_failure: true
+      when: manual
+    - when: on_success
+
 
 freertos-armv5:
   extends: .build-freertos
@@ -151,3 +257,14 @@ freertos-armv5:
     # See the note on linux-qemu-x86.
     CI_ONIRO_BUILD_CACHE: "pub"
     CI_ONIRO_BB_LOCAL_CONF_BB_GENERATE_MIRROR_TARBALLS: 1
+  parallel:
+    matrix:
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "clang"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "llvm"
+      - CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN: "gcc"
+        CI_ONIRO_BB_LOCAL_CONF_RUNTIME: "gnu"
+  rules:
+    - if: '$CI_ONIRO_BB_LOCAL_CONF_TOOLCHAIN == "clang"'
+      allow_failure: true
+      when: manual
+    - when: on_success