diff --git a/src/Composer/Autoload/AutoloadGenerator.php b/src/Composer/Autoload/AutoloadGenerator.php
index cbf3b0aba..161e943ae 100644
--- a/src/Composer/Autoload/AutoloadGenerator.php
+++ b/src/Composer/Autoload/AutoloadGenerator.php
@@ -53,10 +53,15 @@ class AutoloadGenerator
     private $classMapAuthoritative = false;
 
     /**
-     * @var bool|string
+     * @var bool
      */
     private $apcu = false;
 
+    /**
+     * @var string|null
+     */
+    private $apcuPrefix;
+
     /**
      * @var bool
      */
@@ -92,11 +97,13 @@ class AutoloadGenerator
     /**
      * Whether or not generated autoloader considers APCu caching.
      *
-     * @param bool|string $apcu
+     * @param bool        $apcu
+     * @param string|null $apcuPrefix
      */
-    public function setApcu($apcu)
+    public function setApcu($apcu, $apcuPrefix = null)
     {
-        $this->apcu = is_string($apcu) ? $apcu : (bool) $apcu;
+        $this->apcu = (bool) $apcu;
+        $this->apcuPrefix = $apcuPrefix !== null ? (string) $apcuPrefix : $apcuPrefix;
     }
 
     /**
@@ -858,7 +865,7 @@ CLASSMAPAUTHORITATIVE;
         }
 
         if ($this->apcu) {
-            $apcuPrefix = var_export(is_string($this->apcu) ? $this->apcu : substr(base64_encode(md5(uniqid('', true), true)), 0, -3), true);
+            $apcuPrefix = var_export(($this->apcuPrefix ?: substr(base64_encode(md5(uniqid('', true), true)), 0, -3)), true);
             $file .= <<<APCU
         \$loader->setApcuPrefix($apcuPrefix);
 
diff --git a/src/Composer/Command/DumpAutoloadCommand.php b/src/Composer/Command/DumpAutoloadCommand.php
index ee6baabdb..500569a25 100644
--- a/src/Composer/Command/DumpAutoloadCommand.php
+++ b/src/Composer/Command/DumpAutoloadCommand.php
@@ -14,6 +14,7 @@ namespace Composer\Command;
 
 use Composer\Plugin\CommandEvent;
 use Composer\Plugin\PluginEvents;
+use Symfony\Component\Console\Input\InputDefinition;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
@@ -33,7 +34,8 @@ class DumpAutoloadCommand extends BaseCommand
                 new InputOption('no-scripts', null, InputOption::VALUE_NONE, 'Skips the execution of all scripts defined in composer.json file.'),
                 new InputOption('optimize', 'o', InputOption::VALUE_NONE, 'Optimizes PSR0 and PSR4 packages to be loaded with classmaps too, good for production.'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize`.'),
-                new InputOption('apcu', null, InputOption::VALUE_OPTIONAL, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache'),
                 new InputOption('no-dev', null, InputOption::VALUE_NONE, 'Disables autoload-dev rules.'),
                 new InputOption('ignore-platform-req', null, InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY, 'Ignore a specific platform requirement (php & ext- packages).'),
                 new InputOption('ignore-platform-reqs', null, InputOption::VALUE_NONE, 'Ignore all platform requirements (php & ext- packages).'),
@@ -62,7 +64,7 @@ EOT
 
         $optimize = $input->getOption('optimize') || $config->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $config->get('classmap-authoritative');
-        $apcu = strpos($input, '--apcu') !== false || $config->get('apcu-autoloader');
+        $apcu = $input->getOption('apcu') || $config->get('apcu-autoloader');
 
         if ($authoritative) {
             $this->getIO()->write('<info>Generating optimized autoload files (authoritative)</info>');
@@ -77,7 +79,7 @@ EOT
         $generator = $composer->getAutoloadGenerator();
         $generator->setDevMode(!$input->getOption('no-dev'));
         $generator->setClassMapAuthoritative($authoritative);
-        $generator->setApcu($apcu ? $input->getOption('apcu') ?: true : false);
+        $generator->setApcu($apcu, $input->getOption('apcu-prefix'));
         $generator->setRunScripts(!$input->getOption('no-scripts'));
         $generator->setIgnorePlatformRequirements($ignorePlatformReqs);
         $numberOfClasses = $generator->dump($config, $localRepo, $package, $installationManager, 'composer', $optimize);
diff --git a/src/Composer/Command/InstallCommand.php b/src/Composer/Command/InstallCommand.php
index 07f388867..cbcb0eae7 100644
--- a/src/Composer/Command/InstallCommand.php
+++ b/src/Composer/Command/InstallCommand.php
@@ -48,7 +48,8 @@ class InstallCommand extends BaseCommand
                 new InputOption('verbose', 'v|vv|vvv', InputOption::VALUE_NONE, 'Shows more details including new commits pulled in when updating packages.'),
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
-                new InputOption('apcu-autoloader', null, InputOption::VALUE_OPTIONAL, 'Use APCu to cache found/not-found classes (passing an argument sets the APCu prefix)'),
+                new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache'),
                 new InputOption('ignore-platform-req', null, InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY, 'Ignore a specific platform requirement (php & ext- packages).'),
                 new InputOption('ignore-platform-reqs', null, InputOption::VALUE_NONE, 'Ignore all platform requirements (php & ext- packages).'),
                 new InputArgument('packages', InputArgument::IS_ARRAY | InputArgument::OPTIONAL, 'Should not be provided, use composer require instead to add a given package to composer.json.'),
@@ -102,7 +103,7 @@ EOT
 
         $optimize = $input->getOption('optimize-autoloader') || $config->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $config->get('classmap-authoritative');
-        $apcu = strpos($input, '--apcu-autoloader') !== false || $config->get('apcu-autoloader');
+        $apcu = $input->getOption('apcu-autoloader') || $config->get('apcu-autoloader');
 
         $ignorePlatformReqs = $input->getOption('ignore-platform-reqs') ?: ($input->getOption('ignore-platform-req') ?: false);
 
@@ -118,7 +119,7 @@ EOT
             ->setRunScripts(!$input->getOption('no-scripts'))
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu ? $input->getOption('apcu-autoloader') ?: true : false)
+            ->setApcuAutoloader($apcu, $input->getOption('apcu-autoloader-prefix'))
             ->setIgnorePlatformRequirements($ignorePlatformReqs)
         ;
 
diff --git a/src/Composer/Command/RemoveCommand.php b/src/Composer/Command/RemoveCommand.php
index 99be3810b..9e2a46b5a 100644
--- a/src/Composer/Command/RemoveCommand.php
+++ b/src/Composer/Command/RemoveCommand.php
@@ -54,7 +54,8 @@ class RemoveCommand extends BaseCommand
                 new InputOption('ignore-platform-reqs', null, InputOption::VALUE_NONE, 'Ignore all platform requirements (php & ext- packages).'),
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
-                new InputOption('apcu-autoloader', null, InputOption::VALUE_OPTIONAL, 'Use APCu to cache found/not-found classes (passing a string sets the APCu prefix)'),
+                new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache'),
             ))
             ->setHelp(
                 <<<EOT
@@ -227,7 +228,7 @@ EOT
         $updateDevMode = !$input->getOption('update-no-dev');
         $optimize = $input->getOption('optimize-autoloader') || $composer->getConfig()->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $composer->getConfig()->get('classmap-authoritative');
-        $apcu = strpos($input, '--apcu-autoloader') !== false || $composer->getConfig()->get('apcu-autoloader');
+        $apcu = $input->getOption('apcu-autoloader') ?: $composer->getConfig()->get('apcu-autoloader');
 
         $updateAllowTransitiveDependencies = Request::UPDATE_LISTED_WITH_TRANSITIVE_DEPS_NO_ROOT_REQUIRE;
         $flags = '';
@@ -248,7 +249,7 @@ EOT
             ->setDevMode($updateDevMode)
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu ? $input->getOption('apcu-autoloader') ?: true : false)
+            ->setApcuAutoloader($apcu, $input->getOption('apcu-autoloader-prefix'))
             ->setUpdate(true)
             ->setInstall(!$input->getOption('no-install'))
             ->setUpdateAllowList($packages)
diff --git a/src/Composer/Command/RequireCommand.php b/src/Composer/Command/RequireCommand.php
index b1ad95b67..f276b781c 100644
--- a/src/Composer/Command/RequireCommand.php
+++ b/src/Composer/Command/RequireCommand.php
@@ -76,7 +76,8 @@ class RequireCommand extends InitCommand
                 new InputOption('sort-packages', null, InputOption::VALUE_NONE, 'Sorts packages when adding/updating a new dependency'),
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
-                new InputOption('apcu-autoloader', null, InputOption::VALUE_OPTIONAL, 'Use APCu to cache found/not-found classes (passing a string sets the APCu prefix)'),
+                new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache'),
             ))
             ->setHelp(
                 <<<EOT
@@ -269,7 +270,7 @@ EOT
         $updateDevMode = !$input->getOption('update-no-dev');
         $optimize = $input->getOption('optimize-autoloader') || $composer->getConfig()->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $composer->getConfig()->get('classmap-authoritative');
-        $apcu = strpos($input, '--apcu-autoloader') !== false || $composer->getConfig()->get('apcu-autoloader');
+        $apcu = $input->getOption('apcu-autoloader') || $composer->getConfig()->get('apcu-autoloader');
 
         $updateAllowTransitiveDependencies = Request::UPDATE_ONLY_LISTED;
         $flags = '';
@@ -301,7 +302,7 @@ EOT
             ->setRunScripts(!$input->getOption('no-scripts'))
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu ? $input->getOption('apcu-autoloader') ?: true : false)
+            ->setApcuAutoloader($apcu, $input->getOption('apcu-autoloader-prefix'))
             ->setUpdate(true)
             ->setInstall(!$input->getOption('no-install'))
             ->setUpdateAllowTransitiveDependencies($updateAllowTransitiveDependencies)
diff --git a/src/Composer/Command/UpdateCommand.php b/src/Composer/Command/UpdateCommand.php
index bff37129f..cd404e95b 100644
--- a/src/Composer/Command/UpdateCommand.php
+++ b/src/Composer/Command/UpdateCommand.php
@@ -59,7 +59,8 @@ class UpdateCommand extends BaseCommand
                 new InputOption('verbose', 'v|vv|vvv', InputOption::VALUE_NONE, 'Shows more details including new commits pulled in when updating packages.'),
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump.'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
-                new InputOption('apcu-autoloader', null, InputOption::VALUE_OPTIONAL, 'Use APCu to cache found/not-found classes (passing a string sets the APCu prefix)'),
+                new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache'),
                 new InputOption('ignore-platform-req', null, InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY, 'Ignore a specific platform requirement (php & ext- packages).'),
                 new InputOption('ignore-platform-reqs', null, InputOption::VALUE_NONE, 'Ignore all platform requirements (php & ext- packages).'),
                 new InputOption('prefer-stable', null, InputOption::VALUE_NONE, 'Prefer stable versions of dependencies.'),
@@ -189,7 +190,7 @@ EOT
 
         $optimize = $input->getOption('optimize-autoloader') || $config->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $config->get('classmap-authoritative');
-        $apcu = strpos($input, '--apcu-autoloader') !== false || $config->get('apcu-autoloader');
+        $apcu = $input->getOption('apcu-autoloader') || $config->get('apcu-autoloader');
 
         $updateAllowTransitiveDependencies = Request::UPDATE_ONLY_LISTED;
         if ($input->getOption('with-all-dependencies')) {
@@ -210,7 +211,7 @@ EOT
             ->setRunScripts(!$input->getOption('no-scripts'))
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu ? $input->getOption('apcu-autoloader') ?: true : false)
+            ->setApcuAutoloader($apcu, $input->getOption('apcu-autoloader-prefix'))
             ->setUpdate(true)
             ->setInstall(!$input->getOption('no-install'))
             ->setUpdateMirrors($updateMirrors)
diff --git a/src/Composer/Installer.php b/src/Composer/Installer.php
index 17d319e00..50ada1981 100644
--- a/src/Composer/Installer.php
+++ b/src/Composer/Installer.php
@@ -126,6 +126,7 @@ class Installer
     protected $optimizeAutoloader = false;
     protected $classMapAuthoritative = false;
     protected $apcuAutoloader = false;
+    protected $apcuAutoloaderPrefix;
     protected $devMode = false;
     protected $dryRun = false;
     protected $verbose = false;
@@ -307,7 +308,7 @@ class Installer
 
             $this->autoloadGenerator->setDevMode($this->devMode);
             $this->autoloadGenerator->setClassMapAuthoritative($this->classMapAuthoritative);
-            $this->autoloadGenerator->setApcu($this->apcuAutoloader);
+            $this->autoloadGenerator->setApcu($this->apcuAutoloader, $this->apcuAutoloaderPrefix);
             $this->autoloadGenerator->setRunScripts($this->runScripts);
             $this->autoloadGenerator->setIgnorePlatformRequirements($this->ignorePlatformReqs);
             $this->autoloadGenerator->dump($this->config, $localRepo, $this->package, $this->installationManager, 'composer', $this->optimizeAutoloader);
@@ -1023,12 +1024,14 @@ class Installer
     /**
      * Whether or not generated autoloader considers APCu caching.
      *
-     * @param  bool|string $apcuAutoloader
+     * @param  bool        $apcuAutoloader
+     * @param  string|null $apcuAutoloaderPrefix
      * @return Installer
      */
-    public function setApcuAutoloader($apcuAutoloader = false)
+    public function setApcuAutoloader($apcuAutoloader = false, $apcuAutoloaderPrefix = null)
     {
-        $this->apcuAutoloader = is_string($apcuAutoloader) ? $apcuAutoloader : (bool) $apcuAutoloader;
+        $this->apcuAutoloader = $apcuAutoloader;
+        $this->apcuAutoloaderPrefix = $apcuAutoloaderPrefix;
 
         return $this;
     }
diff --git a/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php b/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
index 0cdc58dda..ece9bb2a0 100644
--- a/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
+++ b/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
@@ -853,7 +853,7 @@ EOF;
         file_put_contents($this->vendorDir.'/c/c/foo/ClassMapBaz.php', '<?php class ClassMapBaz {}');
 
         $this->generator->setClassMapAuthoritative(true);
-        $this->generator->setApcu('custom\'Prefix');
+        $this->generator->setApcu(true, 'custom\'Prefix');
         $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_7');
 
         $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated.");