diff --git a/.github/scripts/test.sh b/.github/scripts/test.sh
index 86119da873..d5bac2c520 100755
--- a/.github/scripts/test.sh
+++ b/.github/scripts/test.sh
@@ -1,22 +1,80 @@
 #!/bin/bash
+
+# Catch INT to kill subprocesses
+trap end_make INT
+
 DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
 
-runmats() {
-  echo make allxhelp "$@"
-  make -C ${MACH}/mats allxhelp "$@" 2>&1 | tee -a Make.out | grep '^matting '
+if [ -z ${MACH} ]; then
+    echo "Please define MACH" 1>&2
+    exit 1
+fi
+
+ERR=0
+MATS=${MACH}/mats
+SUMMARYFILE=${MACH}/summary
+declare -a PIDS
+
+# Clean and create summary file
+rm -f "${SUMMARYFILE}"
+touch "${SUMMARYFILE}"
+
+end_make() {
+    echo "Caught Ctrl-C" 1>&2
+    for i in "${!PIDS[@]}"; do
+        local pid="${PID[$i]}"
+        echo "Killing pid ${pid}" 1>&2
+        kill ${pid}
+        rm -r "${MATS}"."${i}"
+    done
+    exit 1
 }
 
-# Split these out so that we get output every 10 minutes on Windows builds.
-runmats o=0
-runmats o=0 cp0=t
-runmats o=3
-runmats o=3 cp0=t
-runmats o=3 cp0=t eval=interpret
+runmats() {
+    local id=$1
+    local matsdest="${MATS}.${id}"
+    cp -r "${MATS}" "${matsdest}"
+    echo make allxhelp "${@:2}"
 
-if [ -f ${MACH}/mats/summary ]; then
-  cat ${MACH}/mats/summary
-  diff -q ${DIR}/summary ${MACH}/mats/summary
-  exit $?
+    # Use -l here so we don't overload machines with less than the number
+    # of parallel tests we force to run
+    make -l$(nproc) -C "${matsdest}" allxhelp "${@:2}" 2>&1 | tee -a Make.out | grep '^matting ' &
+    PIDS[$id]="$!"
+}
+
+ARGS=("o=0"
+      "o=0 cp0=t"
+      "o=3"
+      "o=3 cp0=t"
+      "o=3 cp0=t eval=interpret")
+
+# Run all test classes in parallel
+for i in ${!ARGS[@]}; do
+    runmats $i ${ARGS[$i]}
+done
+
+# Wait for all jobs
+for i in "${!PIDS[@]}"; do
+    pid="${PIDS[$i]}"
+    wait "${pid}"
+
+    # Append current contents to final summary file
+    if [ -f "${MATS}.${i}/summary" ]; then
+        cat "${MATS}.${i}/summary" >> "${SUMMARYFILE}"
+    else
+        echo "ERROR: No summary file for mats.${i}" 1>&2
+        end_make
+        ERR=1
+    fi
+done
+
+# All done - sort lines of file for comparison
+sort "${SUMMARYFILE}" > "${SUMMARYFILE}.sorted"
+
+if [[ "${ERR}" = "1" ]]; then
+    exit 1
 else
-  exit 1
+    cat "${SUMMARYFILE}"
+    diff -q ${DIR}/summary "${SUMMARYFILE}.sorted"    
+    exit $?
 fi