core/modules/path/src/Plugin/migrate/D7PathAliasDeriver.php | 11 +++++++----
 core/modules/path/src/Plugin/migrate/source/d7/UrlAlias.php | 10 ++++++++++
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/core/modules/path/src/Plugin/migrate/D7PathAliasDeriver.php b/core/modules/path/src/Plugin/migrate/D7PathAliasDeriver.php
index 8a23b107a4..cb8bcc6091 100644
--- a/core/modules/path/src/Plugin/migrate/D7PathAliasDeriver.php
+++ b/core/modules/path/src/Plugin/migrate/D7PathAliasDeriver.php
@@ -104,9 +104,9 @@ public function getDerivativeDefinitions($base_plugin_definition) {
               $query->condition('n.nid', $inner_select, 'IN');
               $query->groupBy('type');
               $query->groupBy('name');
-              // @todo use the count?
               $query->addExpression('COUNT(*)', 'count');
-              $aliases_grouped_by_bundle = array_reduce($query->execute()->fetchAllAssoc('type'), function (array $carry, $row) {
+              $rows = $query->execute()->fetchAllAssoc('type');
+              $aliases_grouped_by_bundle = array_reduce($rows, function (array $carry, $row) {
                 $carry[$row->type] = $row->name;
                 return $carry;
               }, []);
@@ -121,9 +121,9 @@ public function getDerivativeDefinitions($base_plugin_definition) {
               $query->groupBy('vid');
               $query->groupBy('machine_name');
               $query->groupBy('name');
-              // @todo use the count?
               $query->addExpression('COUNT(*)', 'count');
-              $aliases_grouped_by_bundle = array_reduce($query->execute()->fetchAllAssoc('machine_name'), function (array $carry, $row) {
+              $rows = $query->execute()->fetchAllAssoc('machine_name');
+              $aliases_grouped_by_bundle = array_reduce($rows, function (array $carry, $row) {
                 $carry[$row->machine_name] = $row->name;
                 return $carry;
               }, []);
@@ -139,6 +139,9 @@ public function getDerivativeDefinitions($base_plugin_definition) {
               $this->derivatives[$derivative_id] = $base_plugin_definition;
               $this->derivatives[$derivative_id]['source']['entity_type_id'] = $entity_type_id;
               $this->derivatives[$derivative_id]['source']['bundle'] = $bundle_id;
+              if (isset($rows) && isset($rows[$bundle_id]) && isset($rows[$bundle_id]->count)) {
+                $this->derivatives[$derivative_id]['source']['__count_at_discovery_time'] = (int) $r[$bundle_id]->count;
+              }
               $this->derivatives[$derivative_id]['label'] = $this->t('@label of @type @entity-type-label', [
                 '@label' => $base_plugin_definition['label'],
                 '@type' => $bundle_label,
diff --git a/core/modules/path/src/Plugin/migrate/source/d7/UrlAlias.php b/core/modules/path/src/Plugin/migrate/source/d7/UrlAlias.php
index 908dd5f5fe..390df7639b 100644
--- a/core/modules/path/src/Plugin/migrate/source/d7/UrlAlias.php
+++ b/core/modules/path/src/Plugin/migrate/source/d7/UrlAlias.php
@@ -17,6 +17,16 @@ class UrlAlias extends UrlAliasBase {
 
   use D7PathAliasDeriverTrait;
 
+  /**
+   * {@inheritdoc}
+   */
+  public function count($refresh = FALSE) {
+    if (!$refresh && isset($this->migration->getSourceConfiguration()['__count_at_discovery_time'])) {
+      return $this->migration->getSourceConfiguration()['__count_at_discovery_time'];
+    }
+    return (int) $this->query()->countQuery()->execute()->fetchField();
+  }
+
   /**
    * {@inheritDoc}
    */