diff --git a/doc/01-basic-usage.md b/doc/01-basic-usage.md
index e0ac13c1c..41e43389b 100644
--- a/doc/01-basic-usage.md
+++ b/doc/01-basic-usage.md
@@ -152,6 +152,13 @@ a Composer `install` to make sure the vendor directory is up in sync with your
 php composer.phar install
 ```
 
+Composer enables reproducible builds by default. This means that running the
+same command multiple times will produce a `vendor/` directory containing files
+that are identical (*except their timestamps*), including the autoloader files.
+It is especially beneficial for environments that require strict
+verification processes, as well as for Linux distributions aiming to package PHP
+applications in a secure and predictable manner.
+
 ## Updating dependencies to their latest versions
 
 As mentioned above, the `composer.lock` file prevents you from automatically getting
diff --git a/doc/06-config.md b/doc/06-config.md
index ac0cdc0e6..a39c2872b 100644
--- a/doc/06-config.md
+++ b/doc/06-config.md
@@ -365,8 +365,10 @@ with other autoloaders.
 
 ## autoloader-suffix
 
-Defaults to `null`. Non-empty string to be used as a suffix for the generated
-Composer autoloader. When null a random one will be generated.
+Defaults to `null`. When set to a non-empty string, this value will be used as a
+suffix for the generated Composer autoloader. If set to `null`, the
+`content-hash` value from the `composer.lock` file will be used if available;
+otherwise, a random suffix will be generated.
 
 ## optimize-autoloader
 
diff --git a/src/Composer/Autoload/AutoloadGenerator.php b/src/Composer/Autoload/AutoloadGenerator.php
index 3e2faa3eb..8ba82090b 100644
--- a/src/Composer/Autoload/AutoloadGenerator.php
+++ b/src/Composer/Autoload/AutoloadGenerator.php
@@ -33,6 +33,7 @@ use Composer\Util\Platform;
 use Composer\Script\ScriptEvents;
 use Composer\Util\PackageSorter;
 use Composer\Json\JsonFile;
+use Composer\Package\Locker;
 
 /**
  * @author Igor Wiedler <igor@wiedler.ch>
@@ -172,7 +173,7 @@ class AutoloadGenerator
      * @throws \Seld\JsonLint\ParsingException
      * @throws \RuntimeException
      */
-    public function dump(Config $config, InstalledRepositoryInterface $localRepo, RootPackageInterface $rootPackage, InstallationManager $installationManager, string $targetDir, bool $scanPsrPackages = false, ?string $suffix = null)
+    public function dump(Config $config, InstalledRepositoryInterface $localRepo, RootPackageInterface $rootPackage, InstallationManager $installationManager, Locker $locker, string $targetDir, bool $scanPsrPackages = false, ?string $suffix = null)
     {
         if ($this->classMapAuthoritative) {
             // Force scanPsrPackages when classmap is authoritative
@@ -405,9 +406,8 @@ EOF;
                 }
             }
 
-            // generate one if we still haven't got a suffix
             if (null === $suffix) {
-                $suffix = md5(uniqid('', true));
+                $suffix = $locker->isLocked() ? $locker->getLockData()['content-hash'] : md5(uniqid('', true));
             }
         }
 
diff --git a/src/Composer/Command/DumpAutoloadCommand.php b/src/Composer/Command/DumpAutoloadCommand.php
index 41a23cd3a..fcd10f2b2 100644
--- a/src/Composer/Command/DumpAutoloadCommand.php
+++ b/src/Composer/Command/DumpAutoloadCommand.php
@@ -100,7 +100,15 @@ EOT
         $generator->setRunScripts(true);
         $generator->setApcu($apcu, $apcuPrefix);
         $generator->setPlatformRequirementFilter($this->getPlatformRequirementFilter($input));
-        $classMap = $generator->dump($config, $localRepo, $package, $installationManager, 'composer', $optimize);
+        $classMap = $generator->dump(
+            $config,
+            $localRepo,
+            $package,
+            $installationManager,
+            $composer->getLocker(),
+            'composer',
+            $optimize
+        );
         $numberOfClasses = count($classMap);
 
         if ($authoritative) {
diff --git a/src/Composer/Command/ReinstallCommand.php b/src/Composer/Command/ReinstallCommand.php
index 990994475..d94ffeb53 100644
--- a/src/Composer/Command/ReinstallCommand.php
+++ b/src/Composer/Command/ReinstallCommand.php
@@ -163,7 +163,15 @@ EOT
             $generator->setClassMapAuthoritative($authoritative);
             $generator->setApcu($apcu, $apcuPrefix);
             $generator->setPlatformRequirementFilter($this->getPlatformRequirementFilter($input));
-            $generator->dump($config, $localRepo, $package, $installationManager, 'composer', $optimize);
+            $generator->dump(
+                $config,
+                $localRepo,
+                $package,
+                $installationManager,
+                $composer->getLocker(),
+                'composer',
+                $optimize
+            );
         }
 
         $eventDispatcher->dispatchScript(ScriptEvents::POST_INSTALL_CMD, $devMode);
diff --git a/src/Composer/Installer.php b/src/Composer/Installer.php
index 3e0f3a5df..7fc4382d1 100644
--- a/src/Composer/Installer.php
+++ b/src/Composer/Installer.php
@@ -349,7 +349,17 @@ class Installer
             $this->autoloadGenerator->setApcu($this->apcuAutoloader, $this->apcuAutoloaderPrefix);
             $this->autoloadGenerator->setRunScripts($this->runScripts);
             $this->autoloadGenerator->setPlatformRequirementFilter($this->platformRequirementFilter);
-            $this->autoloadGenerator->dump($this->config, $localRepo, $this->package, $this->installationManager, 'composer', $this->optimizeAutoloader);
+            $this
+                ->autoloadGenerator
+                ->dump(
+                    $this->config,
+                    $localRepo,
+                    $this->package,
+                    $this->installationManager,
+                    $this->locker,
+                    'composer',
+                    $this->optimizeAutoloader
+                );
         }
 
         if ($this->install && $this->executeOperations) {
diff --git a/src/Composer/Util/Filesystem.php b/src/Composer/Util/Filesystem.php
index 19e0efa8a..5e90e09f3 100644
--- a/src/Composer/Util/Filesystem.php
+++ b/src/Composer/Util/Filesystem.php
@@ -874,10 +874,8 @@ class Filesystem
 
     /**
      * Copy file using stream_copy_to_stream to work around https://bugs.php.net/bug.php?id=6463
-     *
-     * @return void
      */
-    public function safeCopy(string $source, string $target)
+    public function safeCopy(string $source, string $target): void
     {
         if (!file_exists($target) || !file_exists($source) || !$this->filesAreEqual($source, $target)) {
             $sourceHandle = fopen($source, 'r');
@@ -888,6 +886,8 @@ class Filesystem
             stream_copy_to_stream($sourceHandle, $targetHandle);
             fclose($sourceHandle);
             fclose($targetHandle);
+
+            touch($target, (int) filemtime($source), (int) fileatime($source));
         }
     }
 
diff --git a/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php b/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
index cc8c2f0ac..3a9544bb5 100644
--- a/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
+++ b/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
@@ -15,7 +15,6 @@ namespace Composer\Test\Autoload;
 use Composer\Autoload\AutoloadGenerator;
 use Composer\Filter\PlatformRequirementFilter\PlatformRequirementFilterFactory;
 use Composer\IO\BufferIO;
-use Composer\IO\IOInterface;
 use Composer\Package\CompletePackage;
 use Composer\Package\Link;
 use Composer\Package\Version\VersionParser;
@@ -31,6 +30,7 @@ use Composer\Repository\InstalledRepositoryInterface;
 use Composer\Installer\InstallationManager;
 use Composer\Config;
 use Composer\EventDispatcher\EventDispatcher;
+use Composer\Package\Locker;
 use Composer\Util\Platform;
 use PHPUnit\Framework\MockObject\MockObject;
 
@@ -81,6 +81,11 @@ class AutoloadGeneratorTest extends TestCase
      */
     private $io;
 
+    /**
+     * @var Locker
+     */
+    private $locker;
+
     /**
      * @var EventDispatcher&MockObject
      */
@@ -159,6 +164,10 @@ class AutoloadGeneratorTest extends TestCase
             ->getMock();
 
         $this->generator = new AutoloadGenerator($this->eventDispatcher, $this->io);
+
+        $this->locker = $this->getMockBuilder('Composer\Package\Locker')
+            ->disableOriginalConstructor()
+            ->getMock();
     }
 
     protected function tearDown(): void
@@ -208,7 +217,7 @@ class AutoloadGeneratorTest extends TestCase
         $this->fs->ensureDirectoryExists($this->workingDir.'/composersrc');
         file_put_contents($this->workingDir.'/composersrc/foo.php', '<?php class ClassMapFoo {}');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_1');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_1');
 
         // Assert that autoload_namespaces.php was correctly generated.
         $this->assertAutoloadFiles('main', $this->vendorDir.'/composer');
@@ -248,7 +257,7 @@ class AutoloadGeneratorTest extends TestCase
 
         // generate autoload files with the dev mode set to true
         $this->generator->setDevMode(true);
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_1');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_1');
 
         // check standard autoload
         $this->assertAutoloadFiles('main5', $this->vendorDir.'/composer');
@@ -281,7 +290,7 @@ class AutoloadGeneratorTest extends TestCase
         $this->fs->ensureDirectoryExists($this->workingDir.'/devfiles');
         file_put_contents($this->workingDir.'/devfiles/foo.php', '<?php function foo() { echo "foo"; }');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_1');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_1');
 
         // check standard autoload
         $this->assertAutoloadFiles('main4', $this->vendorDir.'/composer');
@@ -316,7 +325,7 @@ class AutoloadGeneratorTest extends TestCase
         $this->fs->ensureDirectoryExists($this->vendorDir.'/composersrc');
         file_put_contents($this->vendorDir.'/composersrc/foo.php', '<?php class ClassMapFoo {}');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_2');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_2');
         $this->assertAutoloadFiles('main3', $this->vendorDir.'/composer');
         $this->assertAutoloadFiles('psr4_3', $this->vendorDir.'/composer', 'psr4');
         $this->assertAutoloadFiles('classmap3', $this->vendorDir.'/composer', 'classmap');
@@ -345,7 +354,7 @@ class AutoloadGeneratorTest extends TestCase
 
         $this->fs->ensureDirectoryExists($this->workingDir.'/composersrc');
         file_put_contents($this->workingDir.'/composersrc/foo.php', '<?php class ClassMapFoo {}');
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_3');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, '_3');
         $this->assertAutoloadFiles('main2', $this->vendorDir.'/composer');
         $this->assertAutoloadFiles('psr4_2', $this->vendorDir.'/composer', 'psr4');
         $this->assertAutoloadFiles('classmap2', $this->vendorDir.'/composer', 'classmap');
@@ -374,7 +383,7 @@ class AutoloadGeneratorTest extends TestCase
         file_put_contents($this->workingDir.'/foo.php', '<?php class FilesFoo {}');
         file_put_contents($this->workingDir.'/bar.php', '<?php class FilesBar {}');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, 'TargetDir');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, 'TargetDir');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_target_dir.php', $this->vendorDir.'/autoload.php');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_real_target_dir.php', $this->vendorDir.'/composer/autoload_real.php');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_static_target_dir.php', $this->vendorDir.'/composer/autoload_static.php');
@@ -400,7 +409,7 @@ class AutoloadGeneratorTest extends TestCase
         file_put_contents($this->workingDir.'/foo.php', '<?php class FilesFoo {}');
         file_put_contents($this->workingDir.'/bar.php', '<?php class FilesBar {}');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, 'FilesWarning');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, 'FilesWarning');
         self::assertFileContentEquals(__DIR__.'/Fixtures/autoload_files_duplicates.php', $this->vendorDir.'/composer/autoload_files.php');
         $expected = '<warning>The following "files" autoload rules are included multiple times, this may cause issues and should be resolved:</warning>'.PHP_EOL.
             '<warning> - $baseDir . \'/foo.php\'</warning>'.PHP_EOL;
@@ -431,7 +440,7 @@ class AutoloadGeneratorTest extends TestCase
         $this->fs->ensureDirectoryExists($this->vendorDir.'/a/a/lib');
         $this->fs->ensureDirectoryExists($this->vendorDir.'/b/b/src');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_5');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, '_5');
         $this->assertAutoloadFiles('vendors', $this->vendorDir.'/composer');
         $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated, even if empty.");
     }
@@ -465,7 +474,7 @@ class AutoloadGeneratorTest extends TestCase
         $this->fs->ensureDirectoryExists($this->vendorDir.'/a/a/src');
         $this->fs->ensureDirectoryExists($this->vendorDir.'/a/a/lib');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_5');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, '_5');
         $this->assertAutoloadFiles('vendors_meta', $this->vendorDir.'/composer');
         $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated, even if empty.");
     }
@@ -498,7 +507,7 @@ class AutoloadGeneratorTest extends TestCase
         $this->fs->ensureDirectoryExists($this->vendorDir.'/a/a/lib');
         $this->fs->ensureDirectoryExists($this->vendorDir.'/b/b/src');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_5');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, '_5');
         $this->assertAutoloadFiles('vendors', $this->vendorDir.'/composer');
         $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated, even if empty.");
     }
@@ -526,7 +535,7 @@ class AutoloadGeneratorTest extends TestCase
         $this->fs->ensureDirectoryExists($this->vendorDir.'/b/b/src/C');
         file_put_contents($this->vendorDir.'/b/b/src/C/C.php', '<?php namespace B\\C; class C {}');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_5');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_5');
 
         $this->assertEquals(
             [
@@ -565,7 +574,7 @@ class AutoloadGeneratorTest extends TestCase
         $this->fs->ensureDirectoryExists($this->vendorDir.'/a/a/lib');
         $this->fs->ensureDirectoryExists($this->vendorDir.'/b/b/src');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_5');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, '_5');
         $this->assertAutoloadFiles('vendors', $this->vendorDir.'/composer');
         $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated, even if empty.");
     }
@@ -617,7 +626,7 @@ class AutoloadGeneratorTest extends TestCase
         file_put_contents($this->vendorDir.'/d/d/src/D.php', '<?php class D {}');
         file_put_contents($this->vendorDir.'/e/e/src/E.php', '<?php class E {}');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_5');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, '_5');
 
         $this->assertAutoloadFiles('classmap9', $this->vendorDir.'/composer', 'classmap');
     }
@@ -656,7 +665,7 @@ class AutoloadGeneratorTest extends TestCase
             ->method('getCanonicalPackages')
             ->will($this->returnValue([$vendorPackage]));
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, 'Phar');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, 'Phar');
 
         $this->assertAutoloadFiles('phar', $this->vendorDir . '/composer');
         $this->assertAutoloadFiles('phar_psr4', $this->vendorDir . '/composer', 'psr4');
@@ -676,7 +685,7 @@ class AutoloadGeneratorTest extends TestCase
             ->method('getCanonicalPackages')
             ->will($this->returnValue([]));
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_8');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_8');
         $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated.");
         $this->assertEquals(
             [
@@ -706,7 +715,7 @@ class AutoloadGeneratorTest extends TestCase
         file_put_contents($this->workingDir.'/psr4/match.php', '<?php namespace psr4; class match {}');
         file_put_contents($this->workingDir.'/psr4/badfile.php', '<?php namespace psr4; class badclass {}');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_1');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_1');
         $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated.");
 
         $expectedClassmap = <<<EOF
@@ -753,7 +762,7 @@ EOF;
         file_put_contents($this->vendorDir.'/b/b/src/b.php', '<?php class ClassMapBar {}');
         file_put_contents($this->vendorDir.'/b/b/lib/c.php', '<?php class ClassMapBaz {}');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_6');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, '_6');
         $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated.");
         $this->assertEquals(
             [
@@ -794,7 +803,7 @@ EOF;
         file_put_contents($this->vendorDir.'/a/a/target/lib/b.php', '<?php class ClassMapBar {}');
         file_put_contents($this->vendorDir.'/b/b/src/c.php', '<?php class ClassMapBaz {}');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_6');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, '_6');
         $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated.");
         $this->assertEquals(
             [
@@ -836,7 +845,7 @@ EOF;
         file_put_contents($this->vendorDir.'/b/b/test.php', '<?php class ClassMapBar {}');
         file_put_contents($this->vendorDir.'/c/c/foo/test.php', '<?php class ClassMapBaz {}');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_7');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, '_7');
         $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated.");
         $this->assertEquals(
             [
@@ -883,7 +892,7 @@ EOF;
 
         $this->generator->setClassMapAuthoritative(true);
         $this->generator->setApcu(true);
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_7');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, '_7');
 
         $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated.");
         $this->assertEquals(
@@ -932,7 +941,7 @@ EOF;
 
         $this->generator->setClassMapAuthoritative(true);
         $this->generator->setApcu(true, 'custom\'Prefix');
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_7');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, '_7');
 
         $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated.");
         $this->assertEquals(
@@ -982,7 +991,7 @@ EOF;
         file_put_contents($this->vendorDir.'/c/c/foo/bar/test4.php', '<?php function testFilesAutoloadGeneration4() {}');
         file_put_contents($this->workingDir.'/root.php', '<?php function testFilesAutoloadGenerationRoot() {}');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, 'FilesAutoload');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, 'FilesAutoload');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_functions.php', $this->vendorDir.'/autoload.php');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_real_functions.php', $this->vendorDir.'/composer/autoload_real.php');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_static_functions.php', $this->vendorDir.'/composer/autoload_static.php');
@@ -1047,20 +1056,20 @@ EOF;
         file_put_contents($this->vendorDir.'/c/c/foo/bar/test4.php', '<?php function testFilesAutoloadGeneration4() {}');
         file_put_contents($this->workingDir.'/root.php', '<?php function testFilesAutoloadGenerationRoot() {}');
 
-        $this->generator->dump($this->config, $this->repository, $autoloadPackage, $this->im, 'composer', false, 'FilesAutoload');
+        $this->generator->dump($this->config, $this->repository, $autoloadPackage, $this->im, $this->locker, 'composer', false, 'FilesAutoload');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_functions.php', $this->vendorDir.'/autoload.php');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_real_functions_with_include_paths.php', $this->vendorDir.'/composer/autoload_real.php');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_static_functions_with_include_paths.php', $this->vendorDir.'/composer/autoload_static.php');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_files_functions.php', $this->vendorDir.'/composer/autoload_files.php');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/include_paths_functions.php', $this->vendorDir.'/composer/include_paths.php');
 
-        $this->generator->dump($this->config, $this->repository, $autoloadPackage, $this->im, 'composer', false, 'FilesAutoload');
+        $this->generator->dump($this->config, $this->repository, $autoloadPackage, $this->im, $this->locker, 'composer', false, 'FilesAutoload');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_functions.php', $this->vendorDir.'/autoload.php');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_real_functions_with_include_paths.php', $this->vendorDir.'/composer/autoload_real.php');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_files_functions_with_removed_extra.php', $this->vendorDir.'/composer/autoload_files.php');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/include_paths_functions_with_removed_extra.php', $this->vendorDir.'/composer/include_paths.php');
 
-        $this->generator->dump($this->config, $this->repository, $notAutoloadPackage, $this->im, 'composer', false, 'FilesAutoload');
+        $this->generator->dump($this->config, $this->repository, $notAutoloadPackage, $this->im, $this->locker, 'composer', false, 'FilesAutoload');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_functions.php', $this->vendorDir.'/autoload.php');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_real_functions_with_removed_include_paths_and_autolad_files.php', $this->vendorDir.'/composer/autoload_real.php');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_static_functions_with_removed_include_paths_and_autolad_files.php', $this->vendorDir.'/composer/autoload_static.php');
@@ -1124,7 +1133,7 @@ EOF;
         file_put_contents($this->vendorDir . '/e/e/testE.php', '<?php function testFilesAutoloadOrderByDependency5() {}');
         file_put_contents($this->workingDir . '/root2.php', '<?php function testFilesAutoloadOrderByDependencyRoot() {}');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, 'FilesAutoloadOrder');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, 'FilesAutoloadOrder');
         $this->assertFileContentEquals(__DIR__ . '/Fixtures/autoload_functions_by_dependency.php', $this->vendorDir . '/autoload.php');
         $this->assertFileContentEquals(__DIR__ . '/Fixtures/autoload_real_files_by_dependency.php', $this->vendorDir . '/composer/autoload_real.php');
         $this->assertFileContentEquals(__DIR__ . '/Fixtures/autoload_static_files_by_dependency.php', $this->vendorDir . '/composer/autoload_static.php');
@@ -1235,7 +1244,7 @@ return array(
 
 EOF;
 
-        $this->generator->dump($this->config, $this->repository, $rootPackage, $this->im, 'composer', true, '_9');
+        $this->generator->dump($this->config, $this->repository, $rootPackage, $this->im, $this->locker, 'composer', true, '_9');
         $this->assertStringEqualsFile($this->vendorDir.'/composer/autoload_namespaces.php', $expectedNamespace);
         $this->assertStringEqualsFile($this->vendorDir.'/composer/autoload_psr4.php', $expectedPsr4);
         $this->assertStringEqualsFile($this->vendorDir.'/composer/autoload_classmap.php', $expectedClassmap);
@@ -1265,7 +1274,7 @@ EOF;
 
         $this->fs->ensureDirectoryExists($this->vendorDir.'/composer');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, "composer", false, '_10');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, '_10');
 
         $this->assertFileContentEquals(__DIR__.'/Fixtures/include_paths.php', $this->vendorDir.'/composer/include_paths.php');
         $this->assertEquals(
@@ -1294,7 +1303,7 @@ EOF;
 
         mkdir($this->vendorDir."/composer", 0777, true);
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, "composer", false, '_11');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, '_11');
 
         $oldIncludePath = get_include_path();
 
@@ -1323,7 +1332,7 @@ EOF;
 
         mkdir($this->vendorDir."/composer", 0777, true);
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, "composer", false, '_12');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, '_12');
 
         $oldIncludePath = get_include_path();
 
@@ -1352,7 +1361,7 @@ EOF;
 
         mkdir($this->vendorDir."/composer", 0777, true);
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, "composer", false, '_12');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, '_12');
 
         $this->assertFileDoesNotExist($this->vendorDir."/composer/include_paths.php");
     }
@@ -1381,7 +1390,7 @@ EOF;
             ->will($this->returnValue([]));
 
         $this->generator->setRunScripts(true);
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_8');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_8');
     }
 
     public function testUseGlobalIncludePath(): void
@@ -1400,7 +1409,7 @@ EOF;
 
         $this->fs->ensureDirectoryExists($this->vendorDir.'/a');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, 'IncludePath');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, 'IncludePath');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_real_include_path.php', $this->vendorDir.'/composer/autoload_real.php');
         $this->assertFileContentEquals(__DIR__.'/Fixtures/autoload_static_include_path.php', $this->vendorDir.'/composer/autoload_static.php');
     }
@@ -1461,7 +1470,7 @@ EOF;
 
         $oldVendorDir = $this->vendorDir;
         $this->vendorDir = $vendorDir;
-        $this->generator->dump($this->config, $this->repository, $package, $im, 'composer', true, '_13');
+        $this->generator->dump($this->config, $this->repository, $package, $im, $this->locker, 'composer', true, '_13');
         $this->vendorDir = $oldVendorDir;
 
         $expectedNamespace = <<<'EOF'
@@ -1551,7 +1560,7 @@ EOF;
         file_put_contents($this->workingDir.'/working-dir/classmap4/foo/classes.php', '<?php namespace Foo; class Boo4 {}');
         file_put_contents($this->workingDir.'/test.php', '<?php class Foo {}');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_14');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_14');
 
         $expectedNamespace = <<<'EOF'
 <?php
@@ -1618,7 +1627,7 @@ EOF;
         $dep->setAutoload([
             'psr-0' => ['Foo' => './src'],
         ]);
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_19');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_19');
 
         $expectedNamespace = <<<'EOF'
 <?php
@@ -1638,7 +1647,7 @@ EOF;
         $dep->setAutoload([
             'psr-4' => ['Acme\Foo\\' => './src-psr4'],
         ]);
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_19');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_19');
 
         $expectedPsr4 = <<<'EOF'
 <?php
@@ -1659,7 +1668,7 @@ EOF;
             'classmap' => ['classmap'],
         ]);
         try {
-            $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_19');
+            $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_19');
         } catch (\RuntimeException $e) {
             $this->assertSame('Could not scan for classes inside "'.$this->vendorDir.'/dep/a/classmap" which does not appear to be a file nor a folder', $e->getMessage());
         }
@@ -1667,7 +1676,7 @@ EOF;
         $dep->setAutoload([
             'files' => ['./test.php'],
         ]);
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_19');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_19');
         $this->assertStringContainsString("\$vendorDir . '/dep/a/test.php',\n", (string) file_get_contents($this->vendorDir.'/composer/autoload_files.php'));
 
         $package->setAutoload([
@@ -1701,7 +1710,7 @@ EOF;
         file_put_contents($this->workingDir.'/Foo/Bar.php', '<?php namespace Foo; class Bar {}');
         file_put_contents($this->workingDir.'/class.php', '<?php namespace Classmap; class Foo {}');
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_15');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_15');
 
         $expectedNamespace = <<<'EOF'
 <?php
@@ -1794,7 +1803,7 @@ return array(
 
 EOF;
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, 'VendorSubstring');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', false, 'VendorSubstring');
         $this->assertStringEqualsFile($this->vendorDir.'/composer/autoload_namespaces.php', $expectedNamespace);
         $this->assertStringEqualsFile($this->vendorDir.'/composer/autoload_psr4.php', $expectedPsr4);
     }
@@ -1862,7 +1871,7 @@ EOF;
             : 'ln -s "' . $target . '" "' . $link . '"';
         exec($command);
 
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_1');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_1');
 
         // Assert that autoload_classmap.php was correctly generated.
         $this->assertAutoloadFiles('classmap', $this->vendorDir.'/composer', 'classmap');
@@ -1894,7 +1903,7 @@ EOF;
             ->will($this->returnValue([]));
 
         $this->generator->setPlatformRequirementFilter(PlatformRequirementFilterFactory::fromBoolOrList($ignorePlatformReqs));
-        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_1');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, $this->locker, 'composer', true, '_1');
 
         if (null === $expectedFixture) {
             $this->assertFileDoesNotExist($this->vendorDir . '/composer/platform_check.php');
diff --git a/tests/Composer/Test/Command/DumpAutoloadCommandTest.php b/tests/Composer/Test/Command/DumpAutoloadCommandTest.php
index de58f5295..88d128772 100644
--- a/tests/Composer/Test/Command/DumpAutoloadCommandTest.php
+++ b/tests/Composer/Test/Command/DumpAutoloadCommandTest.php
@@ -102,4 +102,86 @@ class DumpAutoloadCommandTest extends TestCase
         $this->expectExceptionMessage('You can not use both --no-dev and --dev as they conflict with each other.');
         $appTester->run(['command' => 'dump-autoload', '--dev' => true, '--no-dev' => true]);
     }
+
+    public function testWithCustomAutoloaderSuffix(): void
+    {
+        $dir = $this->initTempComposer([
+            'config' => [
+                'autoloader-suffix' => 'Foobar',
+            ],
+        ]);
+
+        $appTester = $this->getApplicationTester();
+        $this->assertSame(0, $appTester->run(['command' => 'dump-autoload']));
+
+        self::assertStringContainsString('ComposerAutoloaderInitFoobar', (string) file_get_contents($dir . '/vendor/autoload.php'));
+    }
+
+    public function testWithExistingComposerLockAndAutoloaderSuffix(): void
+    {
+        $dir = $this->initTempComposer(
+            [
+                'config' => [
+                    'autoloader-suffix' => 'Foobar',
+                ],
+            ],
+            [],
+            [
+                "_readme" => [
+                    "This file locks the dependencies of your project to a known state",
+                    "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
+                    "This file is @generated automatically"
+                ],
+                "content-hash" => "d751713988987e9331980363e24189ce",
+                "packages" => [],
+                "packages-dev" => [],
+                "aliases" => [],
+                "minimum-stability" => "stable",
+                "stability-flags" => [],
+                "prefer-stable" => false,
+                "prefer-lowest" => false,
+                "platform" => [],
+                "platform-dev" => [],
+                "plugin-api-version" => "2.6.0"
+            ]
+        );
+
+        $appTester = $this->getApplicationTester();
+        $this->assertSame(0, $appTester->run(['command' => 'dump-autoload']));
+
+        self::assertStringContainsString('ComposerAutoloaderInitFoobar', (string) file_get_contents($dir . '/vendor/autoload.php'));
+    }
+
+    public function testWithExistingComposerLockWithoutAutoloaderSuffix(): void
+    {
+        $dir = $this->initTempComposer(
+            [
+                'name' => 'foo/bar',
+            ],
+            [],
+            [
+                "_readme" => [
+                    "This file locks the dependencies of your project to a known state",
+                    "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
+                    "This file is @generated automatically"
+                ],
+                "content-hash" => "2d4a6be9a93712c5d6a119b26734a047",
+                "packages" => [],
+                "packages-dev" => [],
+                "aliases" => [],
+                "minimum-stability" => "stable",
+                "stability-flags" => [],
+                "prefer-stable" => false,
+                "prefer-lowest" => false,
+                "platform" => [],
+                "platform-dev" => [],
+                "plugin-api-version" => "2.6.0"
+            ]
+        );
+
+        $appTester = $this->getApplicationTester();
+        $this->assertSame(0, $appTester->run(['command' => 'dump-autoload']));
+
+        self::assertStringContainsString('ComposerAutoloaderInit2d4a6be9a93712c5d6a119b26734a047', (string) file_get_contents($dir . '/vendor/autoload.php'));
+    }
 }
diff --git a/tests/Composer/Test/TestCase.php b/tests/Composer/Test/TestCase.php
index 357fb9264..a1bbbece1 100644
--- a/tests/Composer/Test/TestCase.php
+++ b/tests/Composer/Test/TestCase.php
@@ -122,9 +122,10 @@ abstract class TestCase extends \PHPUnit\Framework\TestCase
      * @see getApplicationTester
      * @param mixed[] $composerJson
      * @param mixed[] $authJson
+     * @param mixed[] $composerLock
      * @return string the newly created temp dir
      */
-    public function initTempComposer(array $composerJson = [], array $authJson = []): string
+    public function initTempComposer(array $composerJson = [], array $authJson = [], array $composerLock = []): string
     {
         $dir = self::getUniqueTmpDirectory();
 
@@ -150,6 +151,10 @@ abstract class TestCase extends \PHPUnit\Framework\TestCase
         file_put_contents($dir.'/composer.json', JsonFile::encode($composerJson, JSON_UNESCAPED_SLASHES | JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE));
         file_put_contents($dir.'/auth.json', JsonFile::encode($authJson, JSON_UNESCAPED_SLASHES | JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE));
 
+        if ($composerLock !== []) {
+            file_put_contents($dir.'/composer.lock', JsonFile::encode($composerLock, JSON_UNESCAPED_SLASHES | JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE));
+        }
+
         return $dir;
     }