diff --git a/ext/curl/interface.c b/ext/curl/interface.c
index ef0bc09497961..4a9af7cbff21f 100644
--- a/ext/curl/interface.c
+++ b/ext/curl/interface.c
@@ -1345,6 +1345,10 @@ PHP_MINIT_FUNCTION(curl)
 	REGISTER_CURL_CONSTANT(CURLOPT_TCP_FASTOPEN);
 #endif
 
+#if LIBCURL_VERSION_NUM >= 0x073700 /* Available since 7.55.0 */
+	REGISTER_CURL_CONSTANT(CURLOPT_REQUEST_TARGET);
+#endif
+
 #if CURLOPT_FTPASCII != 0
 	REGISTER_CURL_CONSTANT(CURLOPT_FTPASCII);
 #endif
@@ -2367,6 +2371,9 @@ static int _php_curl_setopt(php_curl *ch, zend_long option, zval *zvalue) /* {{{
 #endif
 #if LIBCURL_VERSION_NUM >= 0x072d00 /* Available since 7.45.0 */
 		case CURLOPT_DEFAULT_PROTOCOL:
+#endif
+#if LIBCURL_VERSION_NUM >= 0x073700 /* Available since 7.55.0 */
+		case CURLOPT_REQUEST_TARGET:
 #endif
 		{
 			zend_string *tmp_str;
diff --git a/ext/curl/sync-constants.php b/ext/curl/sync-constants.php
new file mode 100644
index 0000000000000..b7f8919571c54
--- /dev/null
+++ b/ext/curl/sync-constants.php
@@ -0,0 +1,321 @@
+<?php
+
+/**
+ * This script checks the constants defined in the curl PHP extension, against those documented on the cURL website:
+ * https://curl.haxx.se/libcurl/c/symbols-in-versions.html
+ *
+ * See the discussion at: https://github.com/php/php-src/pull/2961
+ */
+
+const CURL_DOC_FILE = 'https://curl.haxx.se/libcurl/c/symbols-in-versions.html';
+
+const SOURCE_FILE = __DIR__ . '/interface.c';
+
+const MIN_SUPPORTED_CURL_VERSION = '7.12.1';
+
+const IGNORED_CONSTANTS = [
+    'CURLOPT_PROGRESSDATA'
+];
+
+$curlConstants   = getCurlConstants();
+$sourceConstants = getSourceConstants();
+
+$notInPHP  = []; // In cURL doc, but missing from PHP
+$notInCurl = []; // In the PHP source, but not in the cURL doc
+$outdated  = []; // In the PHP source, but removed before the minimum supported cURL version
+
+foreach ($curlConstants as $name => [$introduced, $deprecated, $removed]) {
+    $inPHP = in_array($name, $sourceConstants);
+
+    if ($removed !== null) {
+        if (version_compare($removed, MIN_SUPPORTED_CURL_VERSION) < 0) {
+            // constant removed before the minimum supported version
+            continue;
+        }
+    }
+
+    if (! $inPHP) {
+        $notInPHP[$name] = [$introduced, $removed];
+    }
+}
+
+foreach ($sourceConstants as $name) {
+    if (! isset($curlConstants[$name])) {
+        $notInCurl[] = $name;
+        continue;
+    }
+
+    $removed = $curlConstants[$name][2];
+
+    if ($removed === null) {
+        continue;
+    }
+
+    if (version_compare($removed, MIN_SUPPORTED_CURL_VERSION) < 0) {
+        // constant removed before the minimum supported version
+        $outdated[$name] = $removed;
+    }
+}
+
+$allGood = true;
+
+if ($notInPHP) {
+    uasort($notInPHP, function($a, $b) {
+        return version_compare($a[0], $b[0]);
+    });
+
+    $table = new AsciiTable();
+    $table->add('Constant', 'Introduced', '', 'Removed', '');
+
+    foreach ($notInPHP as $name => [$introduced, $removed]) {
+        if ($removed === null) {
+            $removed = '';
+            $removedHex = '';
+        } else {
+            $removedHex = getHexVersion($removed);
+        }
+
+        $table->add($name, $introduced, getHexVersion($introduced), $removed, $removedHex);
+    }
+
+    echo "Constants missing from the PHP source:\n\n";
+    echo $table, "\n";
+
+    $allGood = false;
+}
+
+if ($notInCurl) {
+    $table = new AsciiTable();
+
+    foreach ($notInCurl as $name) {
+        $table->add($name);
+    }
+
+    echo "Constants defined in the PHP source, but absent from the cURL documentation:\n\n";
+    echo $table, "\n";
+
+    $allGood = false;
+}
+
+if ($outdated) {
+    uasort($outdated, function($a, $b) {
+        return version_compare($a, $b);
+    });
+
+    $table = new AsciiTable();
+    $table->add('Constant', 'Removed');
+
+    foreach ($outdated as $name => $version) {
+        $table->add($name, $version);
+    }
+
+    echo "Constants defined in the PHP source, but removed before the minimum supported cURL version:\n\n";
+    echo $table, "\n";
+
+    $allGood = false;
+}
+
+if ($allGood) {
+    echo "All good! Source code and cURL documentation are in sync.\n";
+}
+
+/**
+ * Loads and parses the cURL constants from the online documentation.
+ *
+ * The result is an associative array where the key is the constant name, and the value is a numeric array with:
+ * - the introduced version
+ * - the deprecated version (nullable)
+ * - the removed version (nullable)
+ *
+ * @return array
+ */
+function getCurlConstants() : array
+{
+    $html = file_get_contents(CURL_DOC_FILE);
+
+    // Extract the constant list from the HTML file (located in the only <pre> tag in the page)
+    preg_match('~<pre>([^<]+)</pre>~', $html, $matches);
+    $constantList = $matches[1];
+
+    /**
+     * Parse the cURL constant lines. Possible formats:
+     *
+     * Name                            Introduced    Deprecated  Removed
+     * CURLOPT_CRLFILE                 7.19.0
+     * CURLOPT_DNS_USE_GLOBAL_CACHE    7.9.3         7.11.1
+     * CURLOPT_FTPASCII                7.1           7.11.1      7.15.5
+     * CURLOPT_HTTPREQUEST             7.1           -           7.15.5
+     */
+    $regexp = '/^([A-Za-z0-9_]+) +([0-9\.]+)(?: +([0-9\.\-]+))?(?: +([0-9\.]+))?/m';
+    preg_match_all($regexp, $constantList, $matches, PREG_SET_ORDER);
+
+    $constants = [];
+
+    foreach ($matches as $match) {
+        $name       = $match[1];
+        $introduced = $match[2];
+        $deprecated = $match[3] ?? null;
+        $removed    = $match[4] ?? null;
+
+        if (strpos($name, 'CURLOPT_') !== 0) {
+            // not a CURLOPT_* constant
+            continue;
+        }
+
+        if (in_array($name, IGNORED_CONSTANTS)) {
+            // purposefully ignored constant
+            continue;
+        }
+
+        if ($deprecated === '-') { // deprecated version can be a hyphen
+            $deprecated = null;
+        }
+
+        $constants[$name] = [$introduced, $deprecated, $removed];
+    }
+
+    return $constants;
+}
+
+/**
+ * Parses the defined cURL constants from the PHP extension source code.
+ *
+ * The result is a numeric array whose values are the constant names.
+ *
+ * @return array
+ */
+function getSourceConstants() : array
+{
+    $source = file_get_contents(SOURCE_FILE);
+
+    preg_match_all('/REGISTER_CURL_CONSTANT\(([A-Za-z0-9_]+)\)/', $source, $matches);
+
+    $constants = [];
+
+    foreach ($matches[1] as $name) {
+        if ($name === '__c') { // macro
+            continue;
+        }
+
+        if (strpos($name, 'CURLOPT_') !== 0) {
+            // not a CURLOPT_* constant
+            continue;
+        }
+
+        $constants[] = $name;
+    }
+
+    return $constants;
+}
+
+/**
+ * Converts a version number to its hex representation as used in the extension source code.
+ *
+ * Example: 7.25.1 => 0x071901
+ *
+ * @param string $version
+ *
+ * @return string
+ *
+ * @throws \RuntimeException
+ */
+function getHexVersion(string $version) : string
+{
+    $parts = explode('.', $version);
+
+    if (count($parts) === 2) {
+        $parts[] = '0';
+    }
+
+    if (count($parts) !== 3) {
+        throw new \RuntimeException('Invalid version number: ' . $version);
+    }
+
+    $hex = '0x';
+
+    foreach ($parts as $value) {
+        if (! ctype_digit($value) || strlen($value) > 3) {
+            throw new \RuntimeException('Invalid version number: ' . $version);
+        }
+
+        $value = (int) $value;
+
+        if ($value > 255) {
+            throw new \RuntimeException('Invalid version number: ' . $version);
+        }
+
+        $value = dechex($value);
+
+        if (strlen($value) === 1) {
+            $value = '0' . $value;
+        }
+
+        $hex .= $value;
+    }
+
+    return $hex;
+}
+
+/**
+ * A simple helper to create ASCII tables.
+ * It assumes that the same number of columns is always given to add().
+ */
+class AsciiTable
+{
+    /**
+     * @var array
+     */
+    private $values = [];
+
+    /**
+     * @var array
+     */
+    private $length = [];
+
+    /**
+     * @var int
+     */
+    private $padding = 4;
+
+    /**
+     * @param string[] $values
+     *
+     * @return void
+     */
+    public function add(string ...$values) : void
+    {
+        $this->values[] = $values;
+
+        foreach ($values as $key => $value) {
+            $length = strlen($value);
+
+            if (isset($this->length[$key])) {
+                $this->length[$key] = max($this->length[$key], $length);
+            } else {
+                $this->length[$key] = $length;
+            }
+        }
+    }
+
+    /**
+     * @return string
+     */
+    public function __toString() : string
+    {
+        $result = '';
+
+        foreach ($this->values as $values) {
+            foreach ($values as $key => $value) {
+                if ($key !== 0) {
+                    $result .= str_repeat(' ', $this->padding);
+                }
+
+                $result .= str_pad($value, $this->length[$key]);
+            }
+
+            $result .= "\n";
+        }
+
+        return $result;
+    }
+}