diff --git a/src/Standards/Generic/Sniffs/PHP/SyntaxSniff.php b/src/Standards/Generic/Sniffs/PHP/SyntaxSniff.php
index 7297ebc134..803e3802db 100644
--- a/src/Standards/Generic/Sniffs/PHP/SyntaxSniff.php
+++ b/src/Standards/Generic/Sniffs/PHP/SyntaxSniff.php
@@ -56,10 +56,9 @@ public function process(File $phpcsFile, $stackPtr)
             $this->phpPath = Config::getExecutablePath('php');
         }
 
-        $fileName = escapeshellarg($phpcsFile->getFilename());
-        $cmd      = Common::escapeshellcmd($this->phpPath)." -l -d display_errors=1 -d error_prepend_string='' $fileName 2>&1";
-        $output   = shell_exec($cmd);
-        $matches  = [];
+        $cmd     = $this->getPhpLintCommand($phpcsFile);
+        $output  = shell_exec($cmd);
+        $matches = [];
         if (preg_match('/^.*error:(.*) in .* on line ([0-9]+)/m', trim($output), $matches) === 1) {
             $error = trim($matches[1]);
             $line  = (int) $matches[2];
@@ -72,4 +71,34 @@ public function process(File $phpcsFile, $stackPtr)
     }//end process()
 
 
+    /**
+     * Returns the command used to lint PHP code.
+     *
+     * Uses a different command when the content is provided via STDIN.
+     *
+     * @param \PHP_CodeSniffer\Files\File $phpcsFile The File object.
+     *
+     * @return string The command used to lint PHP code.
+     */
+    private function getPhpLintCommand(File $phpcsFile)
+    {
+        if ($phpcsFile->getFilename() === 'STDIN') {
+            $content = $phpcsFile->getTokensAsString(0, $phpcsFile->numTokens);
+            return sprintf(
+                "echo %s | %s -l -d display_errors=1 -d error_prepend_string='' 2>&1",
+                escapeshellarg($content),
+                Common::escapeshellcmd($this->phpPath)
+            );
+        }
+
+        $fileName = escapeshellarg($phpcsFile->getFilename());
+        return sprintf(
+            "%s -l -d display_errors=1 -d error_prepend_string='' %s 2>&1",
+            Common::escapeshellcmd($this->phpPath),
+            $fileName
+        );
+
+    }//end getPhpLintCommand()
+
+
 }//end class
diff --git a/src/Standards/Generic/Tests/PHP/SyntaxUnitTest.php b/src/Standards/Generic/Tests/PHP/SyntaxUnitTest.php
index 58433eb1d1..115677ae98 100644
--- a/src/Standards/Generic/Tests/PHP/SyntaxUnitTest.php
+++ b/src/Standards/Generic/Tests/PHP/SyntaxUnitTest.php
@@ -10,6 +10,9 @@
 
 namespace PHP_CodeSniffer\Standards\Generic\Tests\PHP;
 
+use PHP_CodeSniffer\Files\DummyFile;
+use PHP_CodeSniffer\Ruleset;
+use PHP_CodeSniffer\Tests\ConfigDouble;
 use PHP_CodeSniffer\Tests\Standards\AbstractSniffUnitTest;
 
 /**
@@ -60,4 +63,108 @@ public function getWarningList()
     }//end getWarningList()
 
 
+    /**
+     * Test the sniff checks syntax when file contents are passed via STDIN.
+     *
+     * Note: this test doesn't run on Windows as PHPCS currently doesn't support STDIN on this OS.
+     *
+     * @param string $content        The content to test.
+     * @param int    $errorCount     The expected number of errors.
+     * @param array  $expectedErrors The expected errors.
+     *
+     * @dataProvider dataStdIn
+     * @requires     OS ^(?!WIN).*
+     *
+     * @return void
+     */
+    public function testStdIn($content, $errorCount, $expectedErrors)
+    {
+        $config            = new ConfigDouble();
+        $config->standards = ['Generic'];
+        $config->sniffs    = ['Generic.PHP.Syntax'];
+
+        $ruleset = new Ruleset($config);
+
+        $file = new DummyFile($content, $ruleset, $config);
+        $file->process();
+
+        $this->assertSame(
+            $errorCount,
+            $file->getErrorCount(),
+            'Error count does not match expected value'
+        );
+        $this->assertSame(
+            0,
+            $file->getWarningCount(),
+            'Warning count does not match expected value'
+        );
+        $this->assertSame(
+            $expectedErrors,
+            $file->getErrors(),
+            'Error list does not match expected errors'
+        );
+
+    }//end testStdIn()
+
+
+    /**
+     * Data provider for testStdIn().
+     *
+     * @return array[]
+     */
+    public function dataStdIn()
+    {
+        // The error message changed in PHP 8+.
+        if (PHP_VERSION_ID >= 80000) {
+            $errorMessage = 'PHP syntax error: syntax error, unexpected token ";", expecting "]"';
+        } else {
+            $errorMessage = 'PHP syntax error: syntax error, unexpected \';\', expecting \']\'';
+        }
+
+        return [
+            'No syntax errors'                                                                => [
+                '<?php $array = [1, 2, 3];',
+                0,
+                [],
+            ],
+            'One syntax error'                                                                => [
+                '<?php $array = [1, 2, 3; // Missing closing bracket.',
+                1,
+                [
+                    1 => [
+                        1 => [
+                            0 => [
+                                'message'  => $errorMessage,
+                                'source'   => 'Generic.PHP.Syntax.PHPSyntax',
+                                'listener' => 'PHP_CodeSniffer\\Standards\\Generic\\Sniffs\\PHP\\SyntaxSniff',
+                                'severity' => 5,
+                                'fixable'  => false,
+                            ],
+                        ],
+                    ],
+                ],
+            ],
+            'Single error reported even when there is more than one syntax error in the file' => [
+                '<?php $array = [1, 2, 3; // Missing closing bracket.
+                $anotherArray = [4, 5, 6; // Another missing closing bracket.',
+                1,
+                [
+                    1 => [
+                        1 => [
+                            0 => [
+                                'message'  => $errorMessage,
+                                'source'   => 'Generic.PHP.Syntax.PHPSyntax',
+                                'listener' => 'PHP_CodeSniffer\\Standards\\Generic\\Sniffs\\PHP\\SyntaxSniff',
+                                'severity' => 5,
+                                'fixable'  => false,
+                            ],
+                        ],
+                    ],
+                ],
+            ],
+        ];
+
+    }//end dataStdIn()
+
+
 }//end class