diff --git a/configuration.sh b/configuration.sh
index 0684b72..d4e2820 100644
--- a/configuration.sh
+++ b/configuration.sh
@@ -95,6 +95,22 @@ DRUPAL_TESTING_SITES_DIRECTORY=${DRUPAL_TESTING_SITES_DIRECTORY:-default}
 # This directory gets removed after successful tests.
 DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY=${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY:-${DRUPAL_TESTING_TEST_BASE_DIRECTORY}/install}
 
+# The version of the project to upgrade from.
+DRUPAL_TESTING_UPGRADE_VERSION=${DRUPAL_TESTING_UPGRADE_VERSION:-""}
+
+# The version of the composer project to upgrade from.
+DRUPAL_TESTING_UPGRADE_COMPOSER_PROJECT_VERSION=${DRUPAL_TESTING_UPGRADE_COMPOSER_PROJECT_VERSION:-""}
+
+# The path to the git checkout under test.
+DRUPAL_TESTING_WORKSPACE=${DRUPAL_TESTING_WORKSPACE:-${GITHUB_WORKSPACE}}
+
+# The version of Drush to use prior to upgrading.
+DRUPAL_TESTING_UPGRADE_DRUSH_VERSION=${DRUPAL_TESTING_UPGRADE_DRUSH_VERSION:-"10.3.6"}
+
+# The location where the project will be copied to and the version to upgrade
+# from will be checkout out here.
+DRUPAL_TESTING_UPGRADE_DRUPAL_INSTALLATION_DIRECTORY=${DRUPAL_TESTING_UPGRADE_DRUPAL_INSTALLATION_DIRECTORY:-${DRUPAL_TESTING_TEST_BASE_DIRECTORY}/old_install}
+
 # The directory, where the tests are located relative to the docroot. This will default to the project directory.
 DRUPAL_TESTING_TEST_LOCATION=${DRUPAL_TESTING_TEST_LOCATION:-""}
 
diff --git a/lib/clean_up.sh b/lib/clean_up.sh
index d2a0812..b0e87ba 100644
--- a/lib/clean_up.sh
+++ b/lib/clean_up.sh
@@ -7,6 +7,11 @@ clean_up() {
         docker rm -f -v "${DRUPAL_TESTING_SELENIUM_DOCKER_NAME}"
     fi
 
+    if [[ -d ${DRUPAL_TESTING_UPGRADE_DRUPAL_INSTALLATION_DIRECTORY} ]]; then
+        chmod -R u+w "${DRUPAL_TESTING_UPGRADE_DRUPAL_INSTALLATION_DIRECTORY}"
+        rm -rf "${DRUPAL_TESTING_UPGRADE_DRUPAL_INSTALLATION_DIRECTORY}"
+    fi
+
     if [[ -d ${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY} ]]; then
         chmod -R u+w "${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
         rm -rf "${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
diff --git a/lib/stage.sh b/lib/stage.sh
index d9e6e74..44cbdd5 100755
--- a/lib/stage.sh
+++ b/lib/stage.sh
@@ -57,6 +57,12 @@ stage_dependency() {
     prepare_build)
         dep="requirements"
         ;;
+    prepare_old_install)
+        dep="requirements"
+        ;;
+    prepare_upgrade)
+        dep="prepare_old_install"
+        ;;
     requirements)
         dep="coding_style"
         ;;
diff --git a/lib/stages/prepare_old_install.sh b/lib/stages/prepare_old_install.sh
new file mode 100644
index 0000000..1f42734
--- /dev/null
+++ b/lib/stages/prepare_old_install.sh
@@ -0,0 +1,62 @@
+#!/usr/bin/env bash
+
+_stage_prepare_old_install() {
+    local docroot
+    docroot=$(get_distribution_docroot false)
+    export COMPOSER_ROOT_VERSION=${DRUPAL_TESTING_UPGRADE_COMPOSER_PROJECT_VERSION}
+
+    # When we test a full project, all we need is the project files itself.
+    if [[ ${DRUPAL_TESTING_PROJECT_TYPE} != "drupal-profile" ]]; then
+        printf "prepare_upgrade is only useful for profiles\n"
+        exit 1
+    fi
+
+    # Checkout the profile and get the version we want to upgrade from.
+    mkdir -p ${DRUPAL_TESTING_UPGRADE_DRUPAL_INSTALLATION_DIRECTORY}
+    cp -R ${DRUPAL_TESTING_WORKSPACE}/. ${DRUPAL_TESTING_UPGRADE_DRUPAL_INSTALLATION_DIRECTORY}
+    git -C ${DRUPAL_TESTING_UPGRADE_DRUPAL_INSTALLATION_DIRECTORY} fetch
+    git -C ${DRUPAL_TESTING_UPGRADE_DRUPAL_INSTALLATION_DIRECTORY} checkout ${DRUPAL_TESTING_UPGRADE_VERSION}
+
+    printf "Prepare composer.json\n\n"
+
+    # Build is based on drupal project
+    composer create-project "${DRUPAL_TESTING_COMPOSER_PROJECT}":"${DRUPAL_TESTING_UPGRADE_COMPOSER_PROJECT_VERSION}" "${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}" --no-interaction --no-install
+
+    composer config "minimum-stability" dev --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+    composer config "prefer-stable" true --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+
+    # Reorder repositories, to make sure, local path is first.
+    composer config repositories.0 path "${DRUPAL_TESTING_UPGRADE_DRUPAL_INSTALLATION_DIRECTORY}" --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+
+    jq '.repositories[0].options = {}' "${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}""/composer.json" | awk 'BEGIN{RS="";getline<"-";print>ARGV[1]}' "${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}""/composer.json"
+    jq '.repositories[0].options.symlink = false' "${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}""/composer.json" | awk 'BEGIN{RS="";getline<"-";print>ARGV[1]}' "${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}""/composer.json"
+
+    composer config repositories.1 composer https://asset-packagist.org --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+    composer config repositories.2 composer https://packages.drupal.org/8 --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+
+    # Enable patching
+    composer require cweagans/composer-patches --no-update --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+    composer config extra.enable-patching true --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+
+    composer require drush/drush:${DRUPAL_TESTING_UPGRADE_DRUSH_VERSION} --prefer-lowest --no-update --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+
+    # Allow required plugins
+    composer config allow-plugins.cweagans/composer-patches true --no-plugins --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+    composer config allow-plugins.drupal/core-composer-scaffold true --no-plugins --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+    composer config allow-plugins.drupal/core-project-message true --no-plugins --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+    composer config allow-plugins.composer/installers true --no-plugins --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+    composer config allow-plugins.oomphinc/composer-installers-extender true --no-plugins --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+    composer config allow-plugins.dealerdirect/phpcodesniffer-composer-installer true --no-plugins --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+    composer config allow-plugins.phpstan/extension-installer true --no-plugins --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+
+    # Install the lowest versions of everything.
+    composer update --prefer-lowest --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+
+    if [[ ! -d ${DRUPAL_TESTING_LOCK_FILES_DIRECTORY} ]]; then
+      mkdir -p "${DRUPAL_TESTING_LOCK_FILES_DIRECTORY}"
+    fi
+
+    # Fake stage completion so that install can run.
+    touch "${DRUPAL_TESTING_LOCK_FILES_DIRECTORY}/build"
+    touch "${DRUPAL_TESTING_LOCK_FILES_DIRECTORY}/prepare_build"
+}
diff --git a/lib/stages/prepare_upgrade.sh b/lib/stages/prepare_upgrade.sh
new file mode 100644
index 0000000..c4fa304
--- /dev/null
+++ b/lib/stages/prepare_upgrade.sh
@@ -0,0 +1,48 @@
+#!/usr/bin/env bash
+
+_stage_prepare_upgrade() {
+    local docroot
+    docroot=$(get_distribution_docroot false)
+
+    # When we test a full project, all we need is the project files itself.
+    if [[ ${DRUPAL_TESTING_PROJECT_TYPE} != "drupal-profile" ]]; then
+        printf "prepare_upgrade is only useful for profiles\n"
+        exit 1
+    fi
+
+    # Add asset-packagist for projects, that require frontend assets
+    if ! composer_repository_exists "https://asset-packagist.org"; then
+        composer config extra."installer-types".0 bower-asset --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+        composer config extra."installer-types".1 npm-asset --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+
+        jq '.extra."installer-paths"."'"${docroot}"'/libraries/{$name}" += ["type:bower-asset", "type:npm-asset"]' "${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}""/composer.json" >"${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}""/composer.tmp"
+        mv "${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}""/composer.tmp" "${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}""/composer.json"
+
+        composer require oomphinc/composer-installers-extender --no-update --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+    fi
+
+    composer require phpspec/prophecy-phpunit:^2 --dev --no-update --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+
+    # Require phpstan.
+    if [ "${DRUPAL_TESTING_TEST_DEPRECATION}" = true ]; then
+        composer require mglaman/phpstan-drupal:^1.1 --dev --no-update --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+        composer require phpstan/phpstan-deprecation-rules:^1.0 --dev --no-update --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+    fi
+
+    # Paratest.
+    if [ "${DRUPAL_TESTING_PARALLEL_TESTING}" = true ]; then
+        composer require brianium/paratest:^6.3 --dev --no-update --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+    fi
+
+    # Set the path repository back to the project under test.
+    composer config repositories.0 path "${DRUPAL_TESTING_WORKSPACE}" --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+
+    # Use jq to find all dev dependencies of the project and add them to root composer file.
+    for dev_dependency in $(jq -r '.["require-dev"?] | keys[] as $k | "\($k):\(.[$k])"' "${DRUPAL_TESTING_PROJECT_BASEDIR}"/composer.json); do
+        composer require "${dev_dependency}" --dev --no-update --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+    done
+
+    # Use the latest drush.
+    composer require drush/drush --no-update --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+
+}