diff --git a/src/php/docker/alpine/Dockerfile b/src/php/docker/alpine/Dockerfile
index a71c2afeccf..67ede050773 100644
--- a/src/php/docker/alpine/Dockerfile
+++ b/src/php/docker/alpine/Dockerfile
@@ -21,8 +21,8 @@ ARG MAKEFLAGS=-j8
 
 WORKDIR /tmp
 
-RUN wget https://phar.phpunit.de/phpunit-5.7.27.phar && \
-  mv phpunit-5.7.27.phar /usr/local/bin/phpunit && \
+RUN wget https://phar.phpunit.de/phpunit-8.5.8.phar && \
+  mv phpunit-8.5.8.phar /usr/local/bin/phpunit && \
   chmod +x /usr/local/bin/phpunit
 
 
diff --git a/src/php/docker/centos7/Dockerfile b/src/php/docker/centos7/Dockerfile
index e6df3ef819e..9c5278e982e 100644
--- a/src/php/docker/centos7/Dockerfile
+++ b/src/php/docker/centos7/Dockerfile
@@ -35,8 +35,8 @@ ARG MAKEFLAGS=-j8
 
 WORKDIR /tmp
 
-RUN wget https://phar.phpunit.de/phpunit-5.7.27.phar && \
-  mv phpunit-5.7.27.phar /usr/local/bin/phpunit && \
+RUN wget https://phar.phpunit.de/phpunit-8.5.8.phar && \
+  mv phpunit-8.5.8.phar /usr/local/bin/phpunit && \
   chmod +x /usr/local/bin/phpunit
 
 
diff --git a/src/php/docker/grpc-ext/Dockerfile b/src/php/docker/grpc-ext/Dockerfile
index 93d0307c4a0..137724bd3ad 100644
--- a/src/php/docker/grpc-ext/Dockerfile
+++ b/src/php/docker/grpc-ext/Dockerfile
@@ -23,8 +23,8 @@ ARG MAKEFLAGS=-j8
 
 WORKDIR /tmp
 
-RUN wget https://phar.phpunit.de/phpunit-5.7.27.phar && \
-  mv phpunit-5.7.27.phar /usr/local/bin/phpunit && \
+RUN wget https://phar.phpunit.de/phpunit-8.5.8.phar && \
+  mv phpunit-8.5.8.phar /usr/local/bin/phpunit && \
   chmod +x /usr/local/bin/phpunit
 
 
diff --git a/src/php/docker/grpc-src/Dockerfile b/src/php/docker/grpc-src/Dockerfile
index 936ddc0da23..bd3acc1caf5 100644
--- a/src/php/docker/grpc-src/Dockerfile
+++ b/src/php/docker/grpc-src/Dockerfile
@@ -23,8 +23,8 @@ ARG MAKEFLAGS=-j8
 
 WORKDIR /tmp
 
-RUN wget https://phar.phpunit.de/phpunit-5.7.27.phar && \
-  mv phpunit-5.7.27.phar /usr/local/bin/phpunit && \
+RUN wget https://phar.phpunit.de/phpunit-8.5.8.phar && \
+  mv phpunit-8.5.8.phar /usr/local/bin/phpunit && \
   chmod +x /usr/local/bin/phpunit
 
 
diff --git a/src/php/docker/i386/Dockerfile b/src/php/docker/i386/Dockerfile
index dff43552558..58556032f91 100644
--- a/src/php/docker/i386/Dockerfile
+++ b/src/php/docker/i386/Dockerfile
@@ -23,8 +23,8 @@ ARG MAKEFLAGS=-j8
 
 WORKDIR /tmp
 
-RUN wget https://phar.phpunit.de/phpunit-5.7.27.phar && \
-  mv phpunit-5.7.27.phar /usr/local/bin/phpunit && \
+RUN wget https://phar.phpunit.de/phpunit-8.5.8.phar && \
+  mv phpunit-8.5.8.phar /usr/local/bin/phpunit && \
   chmod +x /usr/local/bin/phpunit
 
 
diff --git a/src/php/docker/php-future/Dockerfile b/src/php/docker/php-future/Dockerfile
index 95c0ac47a07..1817da14d3f 100644
--- a/src/php/docker/php-future/Dockerfile
+++ b/src/php/docker/php-future/Dockerfile
@@ -23,8 +23,8 @@ ARG MAKEFLAGS=-j8
 
 WORKDIR /tmp
 
-RUN wget https://phar.phpunit.de/phpunit-5.7.27.phar && \
-  mv phpunit-5.7.27.phar /usr/local/bin/phpunit && \
+RUN wget https://phar.phpunit.de/phpunit-8.5.8.phar && \
+  mv phpunit-8.5.8.phar /usr/local/bin/phpunit && \
   chmod +x /usr/local/bin/phpunit
 
 
diff --git a/src/php/docker/php-src/Dockerfile b/src/php/docker/php-src/Dockerfile
index 972a297aafe..f77e3dc2f7c 100644
--- a/src/php/docker/php-src/Dockerfile
+++ b/src/php/docker/php-src/Dockerfile
@@ -23,8 +23,8 @@ RUN apt-get -qq update && apt-get -qq install -y \
 
 WORKDIR /tmp
 
-RUN wget https://phar.phpunit.de/phpunit-5.7.27.phar && \
-  mv phpunit-5.7.27.phar /usr/local/bin/phpunit && \
+RUN wget https://phar.phpunit.de/phpunit-8.5.8.phar && \
+  mv phpunit-8.5.8.phar /usr/local/bin/phpunit && \
   chmod +x /usr/local/bin/phpunit
 
 
diff --git a/src/php/docker/php-zts/Dockerfile b/src/php/docker/php-zts/Dockerfile
index 9bc9d37152d..9889645f994 100644
--- a/src/php/docker/php-zts/Dockerfile
+++ b/src/php/docker/php-zts/Dockerfile
@@ -23,8 +23,8 @@ ARG MAKEFLAGS=-j8
 
 WORKDIR /tmp
 
-RUN wget https://phar.phpunit.de/phpunit-5.7.27.phar && \
-  mv phpunit-5.7.27.phar /usr/local/bin/phpunit && \
+RUN wget https://phar.phpunit.de/phpunit-8.5.8.phar && \
+  mv phpunit-8.5.8.phar /usr/local/bin/phpunit && \
   chmod +x /usr/local/bin/phpunit
 
 
diff --git a/src/php/tests/generated_code/AbstractGeneratedCodeTest.php b/src/php/tests/generated_code/AbstractGeneratedCodeTest.php
index f7b47359992..a68954606f7 100644
--- a/src/php/tests/generated_code/AbstractGeneratedCodeTest.php
+++ b/src/php/tests/generated_code/AbstractGeneratedCodeTest.php
@@ -23,7 +23,7 @@ require_once realpath(dirname(__FILE__).'/../../vendor/autoload.php');
 @include_once dirname(__FILE__).'/math.pb.php';
 @include_once dirname(__FILE__).'/math_grpc_pb.php';
 
-abstract class AbstractGeneratedCodeTest extends PHPUnit_Framework_TestCase
+abstract class AbstractGeneratedCodeTest extends \PHPUnit\Framework\TestCase
 {
     /**
      * These tests require that a server exporting the math service must be
diff --git a/src/php/tests/generated_code/GeneratedCodeTest.php b/src/php/tests/generated_code/GeneratedCodeTest.php
index 91339d390ed..f9fa573bf3e 100755
--- a/src/php/tests/generated_code/GeneratedCodeTest.php
+++ b/src/php/tests/generated_code/GeneratedCodeTest.php
@@ -20,7 +20,7 @@ require_once dirname(__FILE__).'/AbstractGeneratedCodeTest.php';
 
 class GeneratedCodeTest extends AbstractGeneratedCodeTest
 {
-    public function setUp()
+    public function setUp(): void
     {
         self::$client = new Math\MathClient(
             getenv('GRPC_TEST_HOST'), [
@@ -28,7 +28,7 @@ class GeneratedCodeTest extends AbstractGeneratedCodeTest
             ]);
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         self::$client->close();
     }
diff --git a/src/php/tests/generated_code/GeneratedCodeWithCallbackTest.php b/src/php/tests/generated_code/GeneratedCodeWithCallbackTest.php
index 60a90fa025e..fb55d1659cd 100644
--- a/src/php/tests/generated_code/GeneratedCodeWithCallbackTest.php
+++ b/src/php/tests/generated_code/GeneratedCodeWithCallbackTest.php
@@ -20,7 +20,7 @@ require_once dirname(__FILE__).'/AbstractGeneratedCodeTest.php';
 
 class GeneratedCodeWithCallbackTest extends AbstractGeneratedCodeTest
 {
-    public function setUp()
+    public function setUp(): void
     {
         self::$client = new Math\MathClient(
         getenv('GRPC_TEST_HOST'),
@@ -35,7 +35,7 @@ class GeneratedCodeWithCallbackTest extends AbstractGeneratedCodeTest
          ]);
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         self::$client->close();
     }
diff --git a/src/php/tests/unit_tests/CallCredentials2Test.php b/src/php/tests/unit_tests/CallCredentials2Test.php
index c63029f121b..35cf821645c 100644
--- a/src/php/tests/unit_tests/CallCredentials2Test.php
+++ b/src/php/tests/unit_tests/CallCredentials2Test.php
@@ -17,9 +17,9 @@
  *
  */
 
-class CallCredentials2Test extends PHPUnit_Framework_TestCase
+class CallCredentials2Test extends \PHPUnit\Framework\TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         $credentials = Grpc\ChannelCredentials::createSsl(
             file_get_contents(dirname(__FILE__).'/../data/ca.pem'));
@@ -43,7 +43,7 @@ class CallCredentials2Test extends PHPUnit_Framework_TestCase
         );
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         unset($this->channel);
         unset($this->server);
diff --git a/src/php/tests/unit_tests/CallCredentialsTest.php b/src/php/tests/unit_tests/CallCredentialsTest.php
index 818b823da71..a88a2680dbb 100644
--- a/src/php/tests/unit_tests/CallCredentialsTest.php
+++ b/src/php/tests/unit_tests/CallCredentialsTest.php
@@ -17,9 +17,9 @@
  *
  */
 
-class CallCredentialsTest extends PHPUnit_Framework_TestCase
+class CallCredentialsTest extends \PHPUnit\Framework\TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         $this->credentials = Grpc\ChannelCredentials::createSsl(
             file_get_contents(dirname(__FILE__).'/../data/ca.pem'));
@@ -49,7 +49,7 @@ class CallCredentialsTest extends PHPUnit_Framework_TestCase
         );
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         unset($this->channel);
         unset($this->server);
diff --git a/src/php/tests/unit_tests/CallInvokerTest.php b/src/php/tests/unit_tests/CallInvokerTest.php
index 00b5b998652..300d805cb04 100644
--- a/src/php/tests/unit_tests/CallInvokerTest.php
+++ b/src/php/tests/unit_tests/CallInvokerTest.php
@@ -159,16 +159,16 @@ class CallInvokerChangeRequestCall
     }
 }
 
-class CallInvokerTest extends PHPUnit_Framework_TestCase
+class CallInvokerTest extends \PHPUnit\Framework\TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         $this->server = new Grpc\Server([]);
         $this->port = $this->server->addHttp2Port('0.0.0.0:0');
         $this->server->start();
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         unset($this->server);
     }
diff --git a/src/php/tests/unit_tests/CallTest.php b/src/php/tests/unit_tests/CallTest.php
index 23d8e772d0e..4d1be1b1e24 100644
--- a/src/php/tests/unit_tests/CallTest.php
+++ b/src/php/tests/unit_tests/CallTest.php
@@ -16,19 +16,19 @@
  * limitations under the License.
  *
  */
-class CallTest extends PHPUnit_Framework_TestCase
+class CallTest extends \PHPUnit\Framework\TestCase
 {
     public static $server;
     public static $port;
 
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
         self::$server = new Grpc\Server([]);
         self::$port = self::$server->addHttp2Port('0.0.0.0:53000');
         self::$server->start();
     }
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->channel = new Grpc\Channel('localhost:'.self::$port, [
             'force_new' => true,
@@ -38,7 +38,7 @@ class CallTest extends PHPUnit_Framework_TestCase
                                     Grpc\Timeval::infFuture());
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         $this->channel->close();
     }
diff --git a/src/php/tests/unit_tests/ChannelCredentialsTest.php b/src/php/tests/unit_tests/ChannelCredentialsTest.php
index e7e695c9c76..73963cee155 100644
--- a/src/php/tests/unit_tests/ChannelCredentialsTest.php
+++ b/src/php/tests/unit_tests/ChannelCredentialsTest.php
@@ -17,13 +17,13 @@
  *
  */
 
-class ChanellCredentialsTest extends PHPUnit_Framework_TestCase
+class ChanellCredentialsTest extends \PHPUnit\Framework\TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
diff --git a/src/php/tests/unit_tests/ChannelTest.php b/src/php/tests/unit_tests/ChannelTest.php
index 58f96a740b6..8ae394511e8 100644
--- a/src/php/tests/unit_tests/ChannelTest.php
+++ b/src/php/tests/unit_tests/ChannelTest.php
@@ -17,13 +17,13 @@
  *
  */
 
-class ChannelTest extends PHPUnit_Framework_TestCase
+class ChannelTest extends \PHPUnit\Framework\TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         if (!empty($this->channel)) {
             $this->channel->close();
diff --git a/src/php/tests/unit_tests/EndToEndTest.php b/src/php/tests/unit_tests/EndToEndTest.php
index d0965655e0a..08b28e02b81 100644
--- a/src/php/tests/unit_tests/EndToEndTest.php
+++ b/src/php/tests/unit_tests/EndToEndTest.php
@@ -16,9 +16,9 @@
  * limitations under the License.
  *
  */
-class EndToEndTest extends PHPUnit_Framework_TestCase
+class EndToEndTest extends \PHPUnit\Framework\TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         $this->server = new Grpc\Server([]);
         $this->port = $this->server->addHttp2Port('0.0.0.0:0');
@@ -28,7 +28,7 @@ class EndToEndTest extends PHPUnit_Framework_TestCase
         $this->server->start();
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         $this->channel->close();
         unset($this->server);
diff --git a/src/php/tests/unit_tests/InterceptorTest.php b/src/php/tests/unit_tests/InterceptorTest.php
index acd68fc45a2..5e87679a3a2 100644
--- a/src/php/tests/unit_tests/InterceptorTest.php
+++ b/src/php/tests/unit_tests/InterceptorTest.php
@@ -215,9 +215,9 @@ class StopCallInterceptor extends Grpc\Interceptor
     }
 }
 
-class InterceptorTest extends PHPUnit_Framework_TestCase
+class InterceptorTest extends \PHPUnit\Framework\TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         $this->server = new Grpc\Server([]);
         $this->port = $this->server->addHttp2Port('0.0.0.0:0');
@@ -227,7 +227,7 @@ class InterceptorTest extends PHPUnit_Framework_TestCase
         $this->server->start();
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         $this->channel->close();
         unset($this->server);
diff --git a/src/php/tests/unit_tests/PersistentChannelTests/PersistentChannelTest.php b/src/php/tests/unit_tests/PersistentChannelTests/PersistentChannelTest.php
index 7b44221f89b..f10daeb93fb 100644
--- a/src/php/tests/unit_tests/PersistentChannelTests/PersistentChannelTest.php
+++ b/src/php/tests/unit_tests/PersistentChannelTests/PersistentChannelTest.php
@@ -20,13 +20,13 @@
 /**
  * @group persistent_list_bound_tests
  */
-class PersistentListTest extends PHPUnit_Framework_TestCase
+class PersistentListTest extends \PHPUnit\Framework\TestCase
 {
-  public function setUp()
+  public function setUp(): void
   {
   }
 
-  public function tearDown()
+  public function tearDown(): void
   {
     $channel_clean_persistent =
         new Grpc\Channel('localhost:50010', []);
diff --git a/src/php/tests/unit_tests/SecureEndToEndTest.php b/src/php/tests/unit_tests/SecureEndToEndTest.php
index 071598c4c19..da9d9d07fac 100644
--- a/src/php/tests/unit_tests/SecureEndToEndTest.php
+++ b/src/php/tests/unit_tests/SecureEndToEndTest.php
@@ -16,9 +16,9 @@
  * limitations under the License.
  *
  */
-class SecureEndToEndTest extends PHPUnit_Framework_TestCase
+class SecureEndToEndTest extends \PHPUnit\Framework\TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         $credentials = Grpc\ChannelCredentials::createSsl(
             file_get_contents(dirname(__FILE__).'/../data/ca.pem'));
@@ -42,7 +42,7 @@ class SecureEndToEndTest extends PHPUnit_Framework_TestCase
         );
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         $this->channel->close();
         unset($this->server);
diff --git a/src/php/tests/unit_tests/ServerTest.php b/src/php/tests/unit_tests/ServerTest.php
index cab92e59419..b29a6b0eac3 100644
--- a/src/php/tests/unit_tests/ServerTest.php
+++ b/src/php/tests/unit_tests/ServerTest.php
@@ -17,14 +17,14 @@
  *
  */
 
-class ServerTest extends PHPUnit_Framework_TestCase
+class ServerTest extends \PHPUnit\Framework\TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         $this->server = null;
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         unset($this->server);
     }
diff --git a/src/php/tests/unit_tests/TimevalTest.php b/src/php/tests/unit_tests/TimevalTest.php
index 000b2db32d5..1a525088b2d 100644
--- a/src/php/tests/unit_tests/TimevalTest.php
+++ b/src/php/tests/unit_tests/TimevalTest.php
@@ -16,13 +16,13 @@
  * limitations under the License.
  *
  */
-class TimevalTest extends PHPUnit_Framework_TestCase
+class TimevalTest extends \PHPUnit\Framework\TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         unset($this->time);
     }
diff --git a/templates/src/php/docker/download_phpunit.include b/templates/src/php/docker/download_phpunit.include
index 5387119bf55..8d5e17f0ab4 100644
--- a/templates/src/php/docker/download_phpunit.include
+++ b/templates/src/php/docker/download_phpunit.include
@@ -1,3 +1,3 @@
-RUN wget https://phar.phpunit.de/phpunit-5.7.27.phar && ${'\\'}
-  mv phpunit-5.7.27.phar /usr/local/bin/phpunit && ${'\\'}
+RUN wget https://phar.phpunit.de/phpunit-8.5.8.phar && ${'\\'}
+  mv phpunit-8.5.8.phar /usr/local/bin/phpunit && ${'\\'}
   chmod +x /usr/local/bin/phpunit