diff --git a/ci-automation/vendor_test.sh b/ci-automation/vendor_test.sh
index 9e8d25a5ea..77fbd7b4f3 100644
--- a/ci-automation/vendor_test.sh
+++ b/ci-automation/vendor_test.sh
@@ -114,3 +114,272 @@ CIA_FIRST_RUN="${ciavts_first_run}"
 
 # Unset all variables with ciavts_ prefix now.
 unset -v "${!ciavts_@}"
+
+# Prefixes all test names in the tap file with a given prefix, so the
+# test name like "cl.basic" will become "extra-test.[${prefix}].cl.basic".
+#
+# Typical use:
+#   prefix_tap_file "${instance_type}" "${tapfile}"
+#
+# Parameters:
+# 1 - prefix
+# 2 - tap file, modified in place
+function prefix_tap_file() {
+    local prefix="${1}"; shift
+    local tap_file="${1}"; shift
+    # drop the dots from prefix
+    local actual_prefix="extra-test.[${prefix}]."
+
+    sed --in-place --expression 's/^\(\s*\(not\)\?\s*ok[^-]*\s*-\s*\)\(\S\)/\1'"${actual_prefix}"'\3/g' "${tap_file}"
+}
+
+# Filters the test names, so it puts only the real names of the
+# prefixed tests into the chosen variable. For example for prefix
+# "foo", it will ignore the test name like "cl.basic", but will print
+# "cl.internet" for a test name like "extra-test.[foo].cl.internet".
+# "*" is treated specially - it will be inserted into the chosen
+# variable if it is passed.
+#
+# Typical use:
+#   filter_prefixed_tests tests_to_run "${instance_type}" "${@}"
+#   if [[ "${#tests_to_run[@]}" -gt 0 ]]; then …; fi
+#
+# Parameters:
+# 1 - name of an array variable where the filtering results will be stored
+# 2 - prefix
+# @ - test names
+function filter_prefixed_tests() {
+    local var_name="${1}"; shift
+    local prefix="${1}"; shift
+    # rest of the parameters are test names
+    local -n results="${var_name}"
+    local name
+    local stripped_name
+    for name; do
+        stripped_name="${name#extra-test.\[${prefix}\].}"
+        if [[ "${stripped_name}" != "${name}" ]]; then
+            results+=( "${stripped_name}" )
+            continue
+        elif [[ "${name}" = '*' ]]; then
+            results+=( '*' )
+        fi
+    done
+}
+
+# Filters out the extra tests from the passed test names. Ignored test
+# names begin with "extra-test.". The results of the filtering are
+# inserted into the chosen variable.
+#
+# Typical use:
+#   filter_out_prefixed_tests tests_to_run "${@}"
+#   if [[ "${#tests_to_run[@]}" -gt 0 ]]; then …; fi
+#
+# Parameters:
+# 1 - name of an array variable where the filtering results will be stored
+# @ - test names
+function filter_out_prefixed_tests() {
+    local var_name="${1}"; shift
+    local -n results="${var_name}"
+    local name
+    for name; do
+        if [[ "${name#extra-test.}" = "${name}" ]]; then
+            results+=( "${name}" )
+        fi
+    done
+}
+
+# Merges into the first (main) tap file the contents of other tap
+# files. It is very simple - the function assumes that all the tap
+# files begin with a line like:
+#
+# 1..${number_of_tests}
+#
+# Other lines that are processed should begin like:
+#
+# (not)? ok - ${test_name}
+#
+# Any other lines are copied verbatim.
+#
+# The other tap files should already be preprocessed by
+# prefix_tap_file to avoid duplicated test names.
+#
+# Typical use:
+#   merge_tap_files "${tap_file}" extra-validation-*.tap
+#   rm -f extra-validation-*.tap
+#
+# Parameters:
+# 1 - main tap file
+# @ - other tap files
+function merge_tap_files() {
+    local main_tap_file="${1}"; shift
+    # rest of the parameters are other tap files
+
+    local main_test_count=0
+    if [[ -f "${main_tap_file}" ]]; then
+        main_test_count=$(head --lines=1 "${main_tap_file}" | grep --only-matching '[0-9]\+$')
+    fi
+    local other_test_count
+    local other_tap_file
+    local tmp_tap_file="${main_tap_file}.mtf.tmp"
+    for other_tap_file; do
+        if [[ ! -f "${other_tap_file}" ]]; then
+            continue
+        fi
+        other_test_count=$(head --lines=1 "${other_tap_file}" | grep --only-matching '[0-9]\+$' || echo 0 )
+        ((main_test_count+=other_test_count))
+    done
+    echo "1..${main_test_count}" >"${tmp_tap_file}"
+    if [[ -f "${main_tap_file}" ]]; then
+        tail --lines=+2 "${main_tap_file}" >>"${tmp_tap_file}"
+    fi
+    for other_tap_file; do
+        if [[ ! -f "${other_tap_file}" ]]; then
+            continue
+        fi
+        tail --lines=+2 "${other_tap_file}" >>"${tmp_tap_file}"
+    done
+    mv --force "${tmp_tap_file}" "${main_tap_file}"
+}
+
+# Runs or reruns the tests on the main instance and other
+# instances. Other instances usually run a subset of tests only.
+#
+# For this function to work, the caller needs to define two functions
+# beforehand:
+#
+# run_kola_tests that takes the following parameters:
+# 1 - instance type
+# 2 - tap file
+# @ - tests to run
+#
+# query_kola_tests that takes the following parameters:
+# 1 - instance type
+# @ - tests to run
+# This function should print the names of the tests to run. Every line
+# of the output should have one test name to run. Any other cruft in
+# the line will be ignored.
+#
+# Typical use:
+# function run_kola_tests() {
+#     local instance_type="${1}"; shift
+#     local tap_file="${1}"; shift
+#     kola run … "${@}"
+# }
+#
+# function query_kola_tests() {
+#     local instance_type="${1}"; shift
+#     kola list … "${@}"
+# }
+#
+# args=(
+#     "${main_instance}"
+#     "${CIA_TAPFILE}"
+#     "${CIA_FIRST_RUN}"
+#     "${other_instance_types[@]}"
+#     '--'
+#     'cl.internet'
+#     '--'
+#     "${tests_to_run[@]}"
+# )
+# run_kola_tests_on_instances "${args[@]}"
+#
+# Parameters:
+# 1 - main instance type - there all the tests are being run
+# 2 - main tap file
+# 3 - if this is first run (1 if it is, 0 if it is a rerun)
+# @ - other instance types followed by double dash (--) followed by
+#     test names for other instances to filter from the tests to be
+#     run followed by double dash, followed by tests to be run or
+#     rerun
+function run_kola_tests_on_instances() {
+    local main_instance_type="${1}"; shift
+    local main_tapfile="${1}"; shift
+    local is_first_run="${1}"; shift
+    local other_instance_types=()
+    local other_tests=()
+    local arg
+
+    while [[ "${#}" -gt 0 ]]; do
+        arg="${1}"; shift
+        if [[ "${arg}" = '--' ]]; then
+            break
+        fi
+        other_instance_types+=( "${arg}" )
+    done
+
+    while [[ "${#}" -gt 0 ]]; do
+        arg="${1}"; shift
+        if [[ "${arg}" = '--' ]]; then
+            break
+        fi
+        other_tests+=( "${arg}" )
+    done
+
+    # rest of the parameters are tests to be run or rerun
+
+    local instance_type
+    local queried_tests
+    local instance_tests=()
+    local tests_on_instances_running=0
+    local other_tests_for_fgrep
+    other_tests_for_fgrep="$(printf '%s\n' "${other_tests[@]}")"
+
+    for instance_type in "${other_instance_types[@]}"; do
+        # On first run we usually pass the canonical test names like
+        # cl.basic, cl.internet or *, so we decide which tests should
+        # be run on the other instances based on this list. On the
+        # other hand, the rerun will contain names of the failed tests
+        # only, and those are specific - if a test failed on the main
+        # instance, the name of the test will be like cl.basic; if a
+        # test failed on other instance, the name of the test will be
+        # like extra-test.[…].cl.basic. So in case of reruns, we want
+        # to filter the extra tests first then we decide which tests
+        # should be run.
+        if [[ "${is_first_run}" -eq 1 ]]; then
+            set -o noglob # noglob should not be necessary, as
+                          # query_kola_tests shouldn't return a
+                          # wildcard, but better to be safe than sorry
+            queried_tests="$(query_kola_tests "${instance_type}" "${@}")"
+            instance_tests=( $(grep --only-matching --fixed-strings "${other_tests_for_fgrep}" <<<"${queried_tests}" || :) )
+            set +o noglob
+        else
+            filter_prefixed_tests instance_tests "${instance_type}" "${@}"
+        fi
+        if [[ "${#instance_tests[@]}" -gt 0 ]]; then
+            tests_on_instances_running=1
+            (
+                local instance_tapfile="instance_${instance_type}_validate.tap"
+                set +e
+                set -x
+                local output
+                output=$(run_kola_tests "${instance_type}" "${instance_tapfile}" "${instance_tests[@]}" 2>&1)
+                set +x
+                set -e
+                local escaped_instance_type
+                escaped_instance_type="$(sed -e 's/[\/&]/\\&/g' <<<"${instance_type}")"
+                printf "=== START ${instance_type} ===\n%s\n=== END ${instance_type} ===\n" "$(sed -e "s/^/${escaped_instance_type}: /g" <<<"${output}")"
+                prefix_tap_file "${instance_type}" "${instance_tapfile}"
+            ) &
+        fi
+    done
+
+    local -a main_tests
+
+    filter_out_prefixed_tests main_tests "${@}"
+    if [[ "${#main_tests[@]}" -gt 0 ]]; then
+        # run in a subshell, so the set -x and set +e do not pollute
+        # the outer environment
+        (
+            set +e
+            set -x
+            run_kola_tests "${main_instance_type}" "${main_tapfile}" "${main_tests[@]}"
+            true
+        )
+    fi
+
+    if [[ "${tests_on_instances_running}" -eq 1 ]]; then
+        wait
+        merge_tap_files "${main_tapfile}" 'instance_'*'_validate.tap'
+        rm -f 'instance_'*'_validate.tap'
+    fi
+}