diff --git a/.evergreen/run-tests.sh b/.evergreen/run-tests.sh
index 4ff744cd9..abf6aacb1 100755
--- a/.evergreen/run-tests.sh
+++ b/.evergreen/run-tests.sh
@@ -83,30 +83,30 @@ export MONGODB_MULTI_MONGOS_LB_URI="${MONGODB_MULTI_MONGOS_LB_URI}"
 # Run the tests, and store the results in a junit result file
 case "$TESTS" in
    atlas)
-      php vendor/bin/simple-phpunit $PHPUNIT_OPTS --group atlas
+      php vendor/bin/phpunit $PHPUNIT_OPTS --group atlas
       ;;
 
    atlas-data-lake)
-      php vendor/bin/simple-phpunit $PHPUNIT_OPTS --group atlas-data-lake
+      php vendor/bin/phpunit $PHPUNIT_OPTS --group atlas-data-lake
       ;;
 
    csfle)
-      php vendor/bin/simple-phpunit $PHPUNIT_OPTS --group csfle
+      php vendor/bin/phpunit $PHPUNIT_OPTS --group csfle
       ;;
 
    csfle-without-aws-creds)
-      php vendor/bin/simple-phpunit $PHPUNIT_OPTS --group csfle-without-aws-creds
+      php vendor/bin/phpunit $PHPUNIT_OPTS --group csfle-without-aws-creds
       ;;
 
    versioned-api)
-      php vendor/bin/simple-phpunit $PHPUNIT_OPTS --group versioned-api
+      php vendor/bin/phpunit $PHPUNIT_OPTS --group versioned-api
       ;;
 
    serverless)
-      php vendor/bin/simple-phpunit $PHPUNIT_OPTS --group serverless
+      php vendor/bin/phpunit $PHPUNIT_OPTS --group serverless
       ;;
 
    *)
-      php vendor/bin/simple-phpunit $PHPUNIT_OPTS
+      php vendor/bin/phpunit $PHPUNIT_OPTS
       ;;
 esac
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 5e7497813..803eb476d 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -77,7 +77,7 @@ jobs:
           php-ini-values: "zend.assertions=1"
 
       - name: "Run PHPUnit"
-        run: "vendor/bin/simple-phpunit -v"
+        run: "vendor/bin/phpunit -v"
         env:
           SYMFONY_DEPRECATIONS_HELPER: 999999
           MONGODB_URI: ${{ steps.setup-mongodb.outputs.cluster-uri }}
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index ee5ee3a3e..fe387e26d 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -43,14 +43,6 @@ credentials in the connection string (i.e. `MONGODB_URI`) or set the
 Note that `MONGODB_USERNAME` and `MONGODB_PASSWORD` will override any
 credentials present in the connection string.
 
-By default, the `simple-phpunit` binary chooses the correct PHPUnit version for
-the PHP version you are running. To run tests against a specific PHPUnit
-version, use the `SYMFONY_PHPUNIT_VERSION` environment variable:
-
-```console
-$ SYMFONY_PHPUNIT_VERSION=8.5 vendor/bin/simple-phpunit
-```
-
 ### Environment Variables
 
 The test suite references the following environment variables:
diff --git a/composer.json b/composer.json
index a856f4e84..3ac90068c 100644
--- a/composer.json
+++ b/composer.json
@@ -21,9 +21,9 @@
     },
     "require-dev": {
         "doctrine/coding-standard": "^12.0",
+        "phpunit/phpunit": "^9.6",
         "rector/rector": "^1.1",
         "squizlabs/php_codesniffer": "^3.7",
-        "symfony/phpunit-bridge": "^7.1",
         "vimeo/psalm": "^5.13"
     },
     "replace": {
@@ -51,7 +51,7 @@
         "fix:cs": "phpcbf",
         "fix:psalm:baseline": "psalm --set-baseline=psalm-baseline.xml",
         "fix:rector": "rector process --ansi",
-        "test": "simple-phpunit"
+        "test": "phpunit"
     },
     "extra": {
         "branch-alias": {
diff --git a/tests/GridFS/BucketFunctionalTest.php b/tests/GridFS/BucketFunctionalTest.php
index 3456951a9..ccbe6bf02 100644
--- a/tests/GridFS/BucketFunctionalTest.php
+++ b/tests/GridFS/BucketFunctionalTest.php
@@ -871,7 +871,6 @@ public function testDanglingOpenWritableStream(): void
         }
 
         $code = <<<'PHP'
-            require '%s';
             require '%s';
             $client = MongoDB\Tests\FunctionalTestCase::createTestClient();
             $database = $client->selectDatabase(getenv('MONGODB_DATABASE') ?: 'phplib_test');
@@ -888,8 +887,6 @@ public function testDanglingOpenWritableStream(): void
                     sprintf(
                         $code,
                         __DIR__ . '/../../vendor/autoload.php',
-                        // Include the PHPUnit autoload file to ensure PHPUnit classes can be loaded
-                        __DIR__ . '/../../vendor/bin/.phpunit/phpunit/vendor/autoload.php',
                     ),
                 ),
                 '2>&1',
@@ -914,7 +911,6 @@ public function testDanglingOpenWritableStreamWithGlobalStreamWrapperAlias(): vo
         }
 
         $code = <<<'PHP'
-            require '%s';
             require '%s';
             $client = MongoDB\Tests\FunctionalTestCase::createTestClient();
             $database = $client->selectDatabase(getenv('MONGODB_DATABASE') ?: 'phplib_test');
@@ -931,8 +927,6 @@ public function testDanglingOpenWritableStreamWithGlobalStreamWrapperAlias(): vo
                     sprintf(
                         $code,
                         __DIR__ . '/../../vendor/autoload.php',
-                        // Include the PHPUnit autoload file to ensure PHPUnit classes can be loaded
-                        __DIR__ . '/../../vendor/bin/.phpunit/phpunit/vendor/autoload.php',
                     ),
                 ),
                 '2>&1',
diff --git a/tests/SpecTests/DocumentsMatchConstraint.php b/tests/SpecTests/DocumentsMatchConstraint.php
index 16e7914a6..e8d4d0de0 100644
--- a/tests/SpecTests/DocumentsMatchConstraint.php
+++ b/tests/SpecTests/DocumentsMatchConstraint.php
@@ -13,7 +13,6 @@
 use SebastianBergmann\Comparator\ComparisonFailure;
 use SebastianBergmann\Comparator\Factory;
 use stdClass;
-use Symfony\Bridge\PhpUnit\ConstraintTrait;
 
 use function array_values;
 use function get_debug_type;
@@ -36,8 +35,6 @@
  */
 class DocumentsMatchConstraint extends Constraint
 {
-    use ConstraintTrait;
-
     /**
      * TODO: This is not currently used, but was preserved from the design of
      * TestCase::assertMatchesDocument(), which would sort keys and then compare
@@ -65,7 +62,7 @@ public function __construct(array|object $value, private bool $ignoreExtraKeysIn
         $this->comparatorFactory = Factory::getInstance();
     }
 
-    private function doEvaluate($other, $description = '', $returnResult = false)
+    public function evaluate($other, string $description = '', bool $returnResult = false): ?bool
     {
         /* TODO: If ignoreExtraKeys and sortKeys are both false, then we may be
          * able to skip preparation, convert both documents to extended JSON,
@@ -100,6 +97,8 @@ private function doEvaluate($other, $description = '', $returnResult = false)
         if (! $success) {
             $this->fail($other, $description, $this->lastFailure);
         }
+
+        return null;
     }
 
     /** @param string|BSONArray[] $expectedType */
@@ -198,7 +197,7 @@ private function assertEquals(ArrayObject $expected, ArrayObject $actual, bool $
         }
     }
 
-    private function doAdditionalFailureDescription($other)
+    protected function additionalFailureDescription($other): string
     {
         if ($this->lastFailure === null) {
             return '';
@@ -207,12 +206,12 @@ private function doAdditionalFailureDescription($other)
         return $this->lastFailure->getMessage();
     }
 
-    private function doFailureDescription($other)
+    protected function failureDescription($other): string
     {
         return 'two BSON objects are equal';
     }
 
-    private function doMatches($other)
+    protected function matches($other): bool
     {
         /* TODO: If ignoreExtraKeys and sortKeys are both false, then we may be
          * able to skip preparation, convert both documents to extended JSON,
@@ -232,7 +231,7 @@ private function doMatches($other)
         return true;
     }
 
-    private function doToString()
+    public function toString(): string
     {
         return 'matches ' . $this->exporter()->export($this->value);
     }
diff --git a/tests/UnifiedSpecTests/Constraint/IsBsonType.php b/tests/UnifiedSpecTests/Constraint/IsBsonType.php
index 7d17a9af7..e81ccb2a3 100644
--- a/tests/UnifiedSpecTests/Constraint/IsBsonType.php
+++ b/tests/UnifiedSpecTests/Constraint/IsBsonType.php
@@ -23,7 +23,6 @@
 use PHPUnit\Framework\Constraint\Constraint;
 use PHPUnit\Framework\Constraint\LogicalOr;
 use RuntimeException;
-use Symfony\Bridge\PhpUnit\ConstraintTrait;
 
 use function array_keys;
 use function array_map;
@@ -40,8 +39,6 @@
 
 final class IsBsonType extends Constraint
 {
-    use ConstraintTrait;
-
     private static array $types = [
         'double',
         'string',
@@ -88,7 +85,7 @@ public static function anyOf(string ...$types): Constraint
         return LogicalOr::fromConstraints(...array_map(fn ($type) => new self($type), $types));
     }
 
-    private function doMatches($other): bool
+    protected function matches($other): bool
     {
         return match ($this->type) {
             'double' => is_float($other),
@@ -118,7 +115,7 @@ private function doMatches($other): bool
         };
     }
 
-    private function doToString(): string
+    public function toString(): string
     {
         return sprintf('is of BSON type "%s"', $this->type);
     }
diff --git a/tests/UnifiedSpecTests/Constraint/Matches.php b/tests/UnifiedSpecTests/Constraint/Matches.php
index 2a80357fd..4346b6dc8 100644
--- a/tests/UnifiedSpecTests/Constraint/Matches.php
+++ b/tests/UnifiedSpecTests/Constraint/Matches.php
@@ -13,7 +13,6 @@
 use RuntimeException;
 use SebastianBergmann\Comparator\ComparisonFailure;
 use SebastianBergmann\Comparator\Factory;
-use Symfony\Bridge\PhpUnit\ConstraintTrait;
 
 use function array_keys;
 use function count;
@@ -49,8 +48,6 @@
  */
 class Matches extends Constraint
 {
-    use ConstraintTrait;
-
     private mixed $value;
 
     private bool $allowExtraRootKeys;
@@ -69,7 +66,7 @@ public function __construct($value, private ?EntityMap $entityMap = null, $allow
         $this->comparatorFactory = Factory::getInstance();
     }
 
-    private function doEvaluate($other, $description = '', $returnResult = false)
+    public function evaluate($other, $description = '', $returnResult = false): ?bool
     {
         $other = self::prepare($other);
         $success = false;
@@ -104,6 +101,8 @@ private function doEvaluate($other, $description = '', $returnResult = false)
         if (! $success) {
             $this->fail($other, $description, $this->lastFailure);
         }
+
+        return null;
     }
 
     private function assertEquals($expected, $actual, string $keyPath): void
@@ -321,8 +320,7 @@ private function assertMatchesOperator(BSONDocument $operator, $actual, string $
         throw new LogicException('unsupported operator: ' . $name);
     }
 
-    /** @see ConstraintTrait */
-    private function doAdditionalFailureDescription($other)
+    protected function additionalFailureDescription($other): string
     {
         if ($this->lastFailure === null) {
             return '';
@@ -331,14 +329,12 @@ private function doAdditionalFailureDescription($other)
         return $this->lastFailure->getMessage();
     }
 
-    /** @see ConstraintTrait */
-    private function doFailureDescription($other)
+    protected function failureDescription($other): string
     {
         return 'expected value matches actual value';
     }
 
-    /** @see ConstraintTrait */
-    private function doMatches($other)
+    protected function matches($other): bool
     {
         $other = self::prepare($other);
 
@@ -351,8 +347,7 @@ private function doMatches($other)
         return true;
     }
 
-    /** @see ConstraintTrait */
-    private function doToString()
+    public function toString(): string
     {
         return 'matches ' . $this->exporter()->export($this->value);
     }