core/scripts/dev/commit-code-check.sh | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/core/scripts/dev/commit-code-check.sh b/core/scripts/dev/commit-code-check.sh
index 40a0cd733f..e9d0f29327 100755
--- a/core/scripts/dev/commit-code-check.sh
+++ b/core/scripts/dev/commit-code-check.sh
@@ -116,6 +116,12 @@
 # The site root directory is 3 levels up from where the script is located.
 DRUPAL_ROOT=$(dirname $(dirname $(dirname $SCRIPT_ABS_PATH)))
 
+# Detect whether we're testing Drupal core or not.
+IS_DRUPAL_CORE=0
+if [[ "$TOP_LEVEL" == "$DRUPAL_ROOT" ]]; then
+  IS_DRUPAL_CORE=1
+fi
+
 # This variable will be set to one when the file core/phpcs.xml.dist is changed.
 PHPCS_XML_DIST_FILE_CHANGED=0
 
@@ -226,22 +232,25 @@
 fi
 cd "$TOP_LEVEL"
 
-exit 0
-
 # Add a separator line to make the output easier to read.
 printf "\n"
 printf -- '-%.0s' {1..100}
 printf "\n"
 
-# Run PHPStan on all files on DrupalCI or when phpstan files are changed.
+# Run PHPStan on all files on DrupalCI, when phpstan files are changed or when not checking Drupal core.
 # APCu is disabled to ensure that the composer classmap is not corrupted.
-if [[ $PHPSTAN_DIST_FILE_CHANGED == "1" ]] || [[ "$DRUPALCI" == "1" ]]; then
+if [[ $PHPSTAN_DIST_FILE_CHANGED == "1" ]] || [[ "$DRUPALCI" == "1" ]] || [[ "$IS_DRUPAL_CORE" == "0" ]]; then
   printf "\nRunning PHPStan on *all* files.\n"
-  php -d apc.enabled=0 -d apc.enable_cli=0 vendor/bin/phpstan analyze --no-progress --configuration="$TOP_LEVEL/core/phpstan.neon.dist"
+  PHPSTAN_CONFIGURATION="$DRUPAL_ROOT/core/phpstan.neon.dist"
+  # Detect the presence of a phpstan.neon.dist in the current project, or fall back to Drupal core's.
+  if [[ "$IS_DRUPAL_CORE" == "0" ]] && [[ -f "$TOP_LEVEL/phpstan.neon.dist" ]]; then
+    PHPSTAN_CONFIGURATION="$TOP_LEVEL/phpstan.neon.dist"
+  fi
+  php -d apc.enabled=0 -d apc.enable_cli=0 $DRUPAL_ROOT/vendor/bin/phpstan analyze --no-progress --configuration="$PHPSTAN_CONFIGURATION" $TOP_LEVEL
 else
   # Only run PHPStan on changed files locally.
   printf "\nRunning PHPStan on changed files.\n"
-  php -d apc.enabled=0 -d apc.enable_cli=0 vendor/bin/phpstan analyze --no-progress --configuration="$TOP_LEVEL/core/phpstan-partial.neon" $ABS_FILES
+  php -d apc.enabled=0 -d apc.enable_cli=0 $DRUPAL_ROOT/vendor/bin/phpstan analyze --no-progress --configuration="$DRUPAL_ROOT/core/phpstan-partial.neon" $ABS_FILES
 fi
 
 if [ "$?" -ne "0" ]; then
@@ -252,6 +261,8 @@
   printf "\nPHPStan: ${green}passed${reset}\n"
 fi
 
+exit 0
+
 # Add a separator line to make the output easier to read.
 printf "\n"
 printf -- '-%.0s' {1..100}