diff --git a/Zend/tests/gh21639.phpt b/Zend/tests/gh21639.phpt
new file mode 100644
index 000000000000..cebad61a0dbe
--- /dev/null
+++ b/Zend/tests/gh21639.phpt
@@ -0,0 +1,151 @@
+--TEST--
+GH-21639: Frameless calls keep volatile arguments alive
+--FILE--
+<?php
+class ImplodeElement {
+    public function __toString(): string {
+        global $separator, $pieces;
+
+        $separator = null;
+        $pieces = null;
+
+        return "C";
+    }
+}
+
+$separator = str_repeat(",", 1) . " ";
+$pieces = [new ImplodeElement(), 42];
+
+var_dump(implode($separator, $pieces));
+var_dump($separator, $pieces);
+
+class MutatingSeparator {
+    public function __toString(): string {
+        global $piecesFromSeparator;
+
+        $piecesFromSeparator = null;
+
+        return ", ";
+    }
+}
+
+$piecesFromSeparator = ["A", "B"];
+
+var_dump(implode(new MutatingSeparator(), $piecesFromSeparator));
+var_dump($piecesFromSeparator);
+
+class ImplodeElementWithoutSeparator {
+    public function __toString(): string {
+        global $oneArgPieces;
+
+        $oneArgPieces = null;
+
+        return "D";
+    }
+}
+
+$oneArgPieces = [new ImplodeElementWithoutSeparator(), 42];
+
+var_dump(implode($oneArgPieces));
+var_dump($oneArgPieces);
+
+class InArrayNeedle {
+    public function __toString(): string {
+        global $inArrayHaystack;
+
+        $inArrayHaystack = null;
+
+        return "needle";
+    }
+}
+
+$inArrayHaystack = [new InArrayNeedle()];
+
+var_dump(in_array("needle", $inArrayHaystack));
+var_dump($inArrayHaystack);
+
+class StrtrReplacement {
+    public function __toString(): string {
+        global $strtrReplacements;
+
+        $strtrReplacements = null;
+
+        return "b";
+    }
+}
+
+$strtrReplacements = ["a" => new StrtrReplacement()];
+
+var_dump(strtr("a", $strtrReplacements));
+var_dump($strtrReplacements);
+
+class StrReplaceSubject {
+    public function __toString(): string {
+        global $strReplaceSubject;
+
+        $strReplaceSubject = null;
+
+        return "a";
+    }
+}
+
+$strReplaceSubject = [new StrReplaceSubject(), "aa"];
+
+var_dump(str_replace("a", "b", $strReplaceSubject));
+var_dump($strReplaceSubject);
+
+class MinArg {
+    public function __toString(): string {
+        global $minArg;
+
+        $minArg = null;
+
+        return "a";
+    }
+}
+
+$minArg = new MinArg();
+$minResult = min($minArg, "b");
+
+var_dump($minResult instanceof MinArg);
+var_dump($minArg);
+
+class MaxArg {
+    public function __toString(): string {
+        global $maxArg;
+
+        $maxArg = null;
+
+        return "a";
+    }
+}
+
+$maxArg = new MaxArg();
+$maxResult = max("0", $maxArg);
+
+var_dump($maxResult instanceof MaxArg);
+var_dump($maxArg);
+?>
+--EXPECT--
+string(5) "C, 42"
+NULL
+NULL
+string(4) "A, B"
+NULL
+string(3) "D42"
+NULL
+bool(true)
+NULL
+string(1) "b"
+NULL
+array(2) {
+  [0]=>
+  string(1) "b"
+  [1]=>
+  string(2) "bb"
+}
+NULL
+bool(true)
+NULL
+bool(true)
+NULL
diff --git a/Zend/zend_builtin_functions.stub.php b/Zend/zend_builtin_functions.stub.php
index f7009c4ffba6..235ee78fecd3 100644
--- a/Zend/zend_builtin_functions.stub.php
+++ b/Zend/zend_builtin_functions.stub.php
@@ -75,13 +75,13 @@ function method_exists($object_or_class, string $method): bool {}
 
 /**
  * @param object|string $object_or_class
- * @frameless-function {"arity": 2}
+ * @frameless-function {"arity": 2, "needs_arg_copy": true}
  */
 function property_exists($object_or_class, string $property): bool {}
 
 /**
- * @frameless-function {"arity": 1}
- * @frameless-function {"arity": 2}
+ * @frameless-function {"arity": 1, "needs_arg_copy": true}
+ * @frameless-function {"arity": 2, "needs_arg_copy": true}
  */
 function class_exists(string $class, bool $autoload = true): bool {}
 
diff --git a/Zend/zend_builtin_functions_arginfo.h b/Zend/zend_builtin_functions_arginfo.h
index cf34b1c0012d..fdce250e70a4 100644
--- a/Zend/zend_builtin_functions_arginfo.h
+++ b/Zend/zend_builtin_functions_arginfo.h
@@ -1,5 +1,5 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: 3dbc84896823c9aaa9ac8aeef8841266920c3e50 */
+ * Stub hash: f55ea5d885964793884ccae6fd166e92e48abe8d */
 
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_exit, 0, 0, IS_NEVER, 0)
 	ZEND_ARG_TYPE_MASK(0, status, MAY_BE_STRING|MAY_BE_LONG, "0")
@@ -226,15 +226,15 @@ ZEND_END_ARG_INFO()
 
 ZEND_FRAMELESS_FUNCTION(property_exists, 2);
 static const zend_frameless_function_info frameless_function_infos_property_exists[] = {
-	{ ZEND_FRAMELESS_FUNCTION_NAME(property_exists, 2), 2 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(property_exists, 2), 2 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
 ZEND_FRAMELESS_FUNCTION(class_exists, 1);
 ZEND_FRAMELESS_FUNCTION(class_exists, 2);
 static const zend_frameless_function_info frameless_function_infos_class_exists[] = {
-	{ ZEND_FRAMELESS_FUNCTION_NAME(class_exists, 1), 1 },
-	{ ZEND_FRAMELESS_FUNCTION_NAME(class_exists, 2), 2 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(class_exists, 1), 1 | ZEND_FLF_ARG_COPY },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(class_exists, 2), 2 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
diff --git a/Zend/zend_compile.c b/Zend/zend_compile.c
index 5e93c2f864ec..5f1157c448d5 100644
--- a/Zend/zend_compile.c
+++ b/Zend/zend_compile.c
@@ -4668,11 +4668,11 @@ static const zend_frameless_function_info *find_frameless_function_info(zend_ast
 	}
 
 	while (frameless_function_info->handler) {
-		if (frameless_function_info->num_args >= args->children
+		uint32_t num_args = ZEND_FLF_INFO_NUM_ARGS(frameless_function_info);
+		if (num_args >= args->children
 		 && fbc->common.required_num_args <= args->children
 		 && (!(fbc->common.fn_flags & ZEND_ACC_VARIADIC)
-		  || frameless_function_info->num_args == args->children)) {
-			uint32_t num_args = frameless_function_info->num_args;
+		  || num_args == args->children)) {
 			uint32_t offset = find_frameless_function_offset(num_args, frameless_function_info->handler);
 			if (offset == (uint32_t)-1) {
 				continue;
@@ -4688,7 +4688,7 @@ static const zend_frameless_function_info *find_frameless_function_info(zend_ast
 static uint32_t zend_compile_frameless_icall_ex(znode *result, zend_ast_list *args, zend_function *fbc, const zend_frameless_function_info *frameless_function_info, uint32_t type)
 {
 	int lineno = CG(zend_lineno);
-	uint32_t num_args = frameless_function_info->num_args;
+	uint32_t num_args = ZEND_FLF_INFO_NUM_ARGS(frameless_function_info);
 	uint32_t offset = find_frameless_function_offset(num_args, frameless_function_info->handler);
 	znode arg_zvs[3];
 	for (uint32_t i = 0; i < num_args; i++) {
@@ -4705,7 +4705,7 @@ static uint32_t zend_compile_frameless_icall_ex(znode *result, zend_ast_list *ar
 	uint8_t opcode = ZEND_FRAMELESS_ICALL_0 + num_args;
 	uint32_t opnum = get_next_op_number();
 	zend_op *opline = zend_emit_op_tmp(result, opcode, NULL, NULL);
-	opline->extended_value = offset;
+	opline->extended_value = offset | ZEND_FLF_INFO_FLAGS(frameless_function_info);
 	opline->lineno = lineno;
 	if (num_args >= 1) {
 		SET_NODE(opline->op1, &arg_zvs[0]);
diff --git a/Zend/zend_execute.c b/Zend/zend_execute.c
index ea5f55cf6ef7..fef193028726 100644
--- a/Zend/zend_execute.c
+++ b/Zend/zend_execute.c
@@ -1582,15 +1582,20 @@ static zend_never_inline void zend_assign_to_object_dim(zend_object *obj, zval *
 	}
 }
 
-static void frameless_observed_call_copy(zend_execute_data *call, uint32_t arg, zval *zv)
+static zend_always_inline void zend_frameless_copy_arg(zval *dst, zval *src)
 {
-	if (Z_ISUNDEF_P(zv)) {
-		ZVAL_NULL(ZEND_CALL_VAR_NUM(call, arg));
+	if (Z_ISUNDEF_P(src)) {
+		ZVAL_NULL(dst);
 	} else {
-		ZVAL_COPY_DEREF(ZEND_CALL_VAR_NUM(call, arg), zv);
+		ZVAL_COPY_DEREF(dst, src);
 	}
 }
 
+static void frameless_observed_call_copy(zend_execute_data *call, uint32_t arg, zval *zv)
+{
+	zend_frameless_copy_arg(ZEND_CALL_VAR_NUM(call, arg), zv);
+}
+
 ZEND_API void zend_frameless_observed_call(zend_execute_data *execute_data)
 {
 	const zend_op *opline = EX(opline);
diff --git a/Zend/zend_frameless_function.h b/Zend/zend_frameless_function.h
index d64ca7ee15e2..1bdeb29ba2a0 100644
--- a/Zend/zend_frameless_function.h
+++ b/Zend/zend_frameless_function.h
@@ -36,8 +36,14 @@
 #define ZEND_FRAMELESS_FUNCTION_NAME(name, arity) zflf_##name##_##arity
 #define ZEND_OP_IS_FRAMELESS_ICALL(opcode) ((opcode) >= ZEND_FRAMELESS_ICALL_0 && (opcode) <= ZEND_FRAMELESS_ICALL_3)
 #define ZEND_FLF_NUM_ARGS(opcode) ((opcode) - ZEND_FRAMELESS_ICALL_0)
-#define ZEND_FLF_FUNC(opline) (zend_flf_functions[(opline)->extended_value])
-#define ZEND_FLF_HANDLER(opline) (zend_flf_handlers[(opline)->extended_value])
+#define ZEND_FLF_ARG_COPY (1u << 31)
+#define ZEND_FLF_NUM_ARGS_MASK (~ZEND_FLF_ARG_COPY)
+#define ZEND_FLF_INFO_NUM_ARGS(info) ((info)->num_args & ZEND_FLF_NUM_ARGS_MASK)
+#define ZEND_FLF_INFO_FLAGS(info) ((info)->num_args & ZEND_FLF_ARG_COPY)
+#define ZEND_FLF_OFFSET(opline) ((opline)->extended_value & ZEND_FLF_NUM_ARGS_MASK)
+#define ZEND_FLF_USES_ARG_COPY(opline) ((opline)->extended_value & ZEND_FLF_ARG_COPY)
+#define ZEND_FLF_FUNC(opline) (zend_flf_functions[ZEND_FLF_OFFSET(opline)])
+#define ZEND_FLF_HANDLER(opline) (zend_flf_handlers[ZEND_FLF_OFFSET(opline)])
 
 #define ZEND_FRAMELESS_FUNCTION(name, arity) \
 	void ZEND_FRAMELESS_FUNCTION_NAME(name, arity)(ZEND_FRAMELESS_FUNCTION_PARAMETERS_##arity)
diff --git a/Zend/zend_vm_def.h b/Zend/zend_vm_def.h
index 34906e1bfcca..c2f645978443 100644
--- a/Zend/zend_vm_def.h
+++ b/Zend/zend_vm_def.h
@@ -9713,7 +9713,14 @@ ZEND_VM_HANDLER(205, ZEND_FRAMELESS_ICALL_1, ANY, UNUSED, SPEC(OBSERVER))
 #endif
 	{
 		zend_frameless_function_1 function = (zend_frameless_function_1)ZEND_FLF_HANDLER(opline);
-		function(result, arg1);
+		if (UNEXPECTED(ZEND_FLF_USES_ARG_COPY(opline))) {
+			zval arg1_copy;
+			zend_frameless_copy_arg(&arg1_copy, arg1);
+			function(result, &arg1_copy);
+			zval_ptr_dtor_nogc(&arg1_copy);
+		} else {
+			function(result, arg1);
+		}
 	}
 	FREE_OP1();
 	ZEND_VM_NEXT_OPCODE_CHECK_EXCEPTION();
@@ -9741,7 +9748,16 @@ ZEND_VM_HANDLER(206, ZEND_FRAMELESS_ICALL_2, ANY, ANY, SPEC(OBSERVER))
 #endif
 	{
 		zend_frameless_function_2 function = (zend_frameless_function_2)ZEND_FLF_HANDLER(opline);
-		function(result, arg1, arg2);
+		if (UNEXPECTED(ZEND_FLF_USES_ARG_COPY(opline))) {
+			zval arg1_copy, arg2_copy;
+			zend_frameless_copy_arg(&arg1_copy, arg1);
+			zend_frameless_copy_arg(&arg2_copy, arg2);
+			function(result, &arg1_copy, &arg2_copy);
+			zval_ptr_dtor_nogc(&arg1_copy);
+			zval_ptr_dtor_nogc(&arg2_copy);
+		} else {
+			function(result, arg1, arg2);
+		}
 	}
 
 	FREE_OP1();
@@ -9777,7 +9793,18 @@ ZEND_VM_HANDLER(207, ZEND_FRAMELESS_ICALL_3, ANY, ANY, SPEC(OBSERVER))
 #endif
 	{
 		zend_frameless_function_3 function = (zend_frameless_function_3)ZEND_FLF_HANDLER(opline);
-		function(result, arg1, arg2, arg3);
+		if (UNEXPECTED(ZEND_FLF_USES_ARG_COPY(opline))) {
+			zval arg1_copy, arg2_copy, arg3_copy;
+			zend_frameless_copy_arg(&arg1_copy, arg1);
+			zend_frameless_copy_arg(&arg2_copy, arg2);
+			zend_frameless_copy_arg(&arg3_copy, arg3);
+			function(result, &arg1_copy, &arg2_copy, &arg3_copy);
+			zval_ptr_dtor_nogc(&arg1_copy);
+			zval_ptr_dtor_nogc(&arg2_copy);
+			zval_ptr_dtor_nogc(&arg3_copy);
+		} else {
+			function(result, arg1, arg2, arg3);
+		}
 	}
 
 	FREE_OP1();
diff --git a/Zend/zend_vm_execute.h b/Zend/zend_vm_execute.h
index d4b2aff1907b..c6fef89352d8 100644
--- a/Zend/zend_vm_execute.h
+++ b/Zend/zend_vm_execute.h
@@ -3736,7 +3736,16 @@ static ZEND_OPCODE_HANDLER_RET ZEND_FASTCALL ZEND_FRAMELESS_ICALL_2_SPEC_HANDLER
 #endif
 	{
 		zend_frameless_function_2 function = (zend_frameless_function_2)ZEND_FLF_HANDLER(opline);
-		function(result, arg1, arg2);
+		if (UNEXPECTED(ZEND_FLF_USES_ARG_COPY(opline))) {
+			zval arg1_copy, arg2_copy;
+			zend_frameless_copy_arg(&arg1_copy, arg1);
+			zend_frameless_copy_arg(&arg2_copy, arg2);
+			function(result, &arg1_copy, &arg2_copy);
+			zval_ptr_dtor_nogc(&arg1_copy);
+			zval_ptr_dtor_nogc(&arg2_copy);
+		} else {
+			function(result, arg1, arg2);
+		}
 	}
 
 	FREE_OP(opline->op1_type, opline->op1.var);
@@ -3770,7 +3779,16 @@ static ZEND_OPCODE_HANDLER_RET ZEND_FASTCALL ZEND_FRAMELESS_ICALL_2_SPEC_OBSERVE
 #endif
 	{
 		zend_frameless_function_2 function = (zend_frameless_function_2)ZEND_FLF_HANDLER(opline);
-		function(result, arg1, arg2);
+		if (UNEXPECTED(ZEND_FLF_USES_ARG_COPY(opline))) {
+			zval arg1_copy, arg2_copy;
+			zend_frameless_copy_arg(&arg1_copy, arg1);
+			zend_frameless_copy_arg(&arg2_copy, arg2);
+			function(result, &arg1_copy, &arg2_copy);
+			zval_ptr_dtor_nogc(&arg1_copy);
+			zval_ptr_dtor_nogc(&arg2_copy);
+		} else {
+			function(result, arg1, arg2);
+		}
 	}
 
 	FREE_OP(opline->op1_type, opline->op1.var);
@@ -3806,7 +3824,18 @@ static ZEND_OPCODE_HANDLER_RET ZEND_FASTCALL ZEND_FRAMELESS_ICALL_3_SPEC_HANDLER
 #endif
 	{
 		zend_frameless_function_3 function = (zend_frameless_function_3)ZEND_FLF_HANDLER(opline);
-		function(result, arg1, arg2, arg3);
+		if (UNEXPECTED(ZEND_FLF_USES_ARG_COPY(opline))) {
+			zval arg1_copy, arg2_copy, arg3_copy;
+			zend_frameless_copy_arg(&arg1_copy, arg1);
+			zend_frameless_copy_arg(&arg2_copy, arg2);
+			zend_frameless_copy_arg(&arg3_copy, arg3);
+			function(result, &arg1_copy, &arg2_copy, &arg3_copy);
+			zval_ptr_dtor_nogc(&arg1_copy);
+			zval_ptr_dtor_nogc(&arg2_copy);
+			zval_ptr_dtor_nogc(&arg3_copy);
+		} else {
+			function(result, arg1, arg2, arg3);
+		}
 	}
 
 	FREE_OP(opline->op1_type, opline->op1.var);
@@ -3846,7 +3875,18 @@ static ZEND_OPCODE_HANDLER_RET ZEND_FASTCALL ZEND_FRAMELESS_ICALL_3_SPEC_OBSERVE
 #endif
 	{
 		zend_frameless_function_3 function = (zend_frameless_function_3)ZEND_FLF_HANDLER(opline);
-		function(result, arg1, arg2, arg3);
+		if (UNEXPECTED(ZEND_FLF_USES_ARG_COPY(opline))) {
+			zval arg1_copy, arg2_copy, arg3_copy;
+			zend_frameless_copy_arg(&arg1_copy, arg1);
+			zend_frameless_copy_arg(&arg2_copy, arg2);
+			zend_frameless_copy_arg(&arg3_copy, arg3);
+			function(result, &arg1_copy, &arg2_copy, &arg3_copy);
+			zval_ptr_dtor_nogc(&arg1_copy);
+			zval_ptr_dtor_nogc(&arg2_copy);
+			zval_ptr_dtor_nogc(&arg3_copy);
+		} else {
+			function(result, arg1, arg2, arg3);
+		}
 	}
 
 	FREE_OP(opline->op1_type, opline->op1.var);
@@ -4271,7 +4311,14 @@ static ZEND_OPCODE_HANDLER_RET ZEND_FASTCALL ZEND_FRAMELESS_ICALL_1_SPEC_UNUSED_
 #endif
 	{
 		zend_frameless_function_1 function = (zend_frameless_function_1)ZEND_FLF_HANDLER(opline);
-		function(result, arg1);
+		if (UNEXPECTED(ZEND_FLF_USES_ARG_COPY(opline))) {
+			zval arg1_copy;
+			zend_frameless_copy_arg(&arg1_copy, arg1);
+			function(result, &arg1_copy);
+			zval_ptr_dtor_nogc(&arg1_copy);
+		} else {
+			function(result, arg1);
+		}
 	}
 	FREE_OP(opline->op1_type, opline->op1.var);
 	ZEND_VM_NEXT_OPCODE_CHECK_EXCEPTION();
@@ -4297,7 +4344,14 @@ static ZEND_OPCODE_HANDLER_RET ZEND_FASTCALL ZEND_FRAMELESS_ICALL_1_SPEC_OBSERVE
 #endif
 	{
 		zend_frameless_function_1 function = (zend_frameless_function_1)ZEND_FLF_HANDLER(opline);
-		function(result, arg1);
+		if (UNEXPECTED(ZEND_FLF_USES_ARG_COPY(opline))) {
+			zval arg1_copy;
+			zend_frameless_copy_arg(&arg1_copy, arg1);
+			function(result, &arg1_copy);
+			zval_ptr_dtor_nogc(&arg1_copy);
+		} else {
+			function(result, arg1);
+		}
 	}
 	FREE_OP(opline->op1_type, opline->op1.var);
 	ZEND_VM_NEXT_OPCODE_CHECK_EXCEPTION();
diff --git a/build/gen_stub.php b/build/gen_stub.php
index 28b168c72642..f8cd466cf94d 100755
--- a/build/gen_stub.php
+++ b/build/gen_stub.php
@@ -1406,7 +1406,11 @@ public function getFramelessDeclaration(FuncInfo $funcInfo): ?string {
 
         $code .= 'static const zend_frameless_function_info ' . $this->getFramelessFunctionInfosName() . "[] = {\n";
         foreach ($this->framelessFunctionInfos as $framelessFunctionInfo) {
-            $code .= "\t{ ZEND_FRAMELESS_FUNCTION_NAME({$this->name->getFunctionName()}, {$framelessFunctionInfo->arity}), {$framelessFunctionInfo->arity} },\n";
+            $numArgs = (string) $framelessFunctionInfo->arity;
+            if ($framelessFunctionInfo->needsArgCopy) {
+                $numArgs .= " | ZEND_FLF_ARG_COPY";
+            }
+            $code .= "\t{ ZEND_FRAMELESS_FUNCTION_NAME({$this->name->getFunctionName()}, {$framelessFunctionInfo->arity}), $numArgs },\n";
         }
         $code .= "\t{ 0 },\n";
         $code .= "};\n";
@@ -4166,6 +4170,7 @@ function parseDocComment(DocComment $comment): array {
 
 class FramelessFunctionInfo {
     public int $arity;
+    public bool $needsArgCopy = false;
 }
 
 function parseFramelessFunctionInfo(string $json): FramelessFunctionInfo {
@@ -4173,6 +4178,7 @@ function parseFramelessFunctionInfo(string $json): FramelessFunctionInfo {
     $json = json_decode($json, true);
     $framelessFunctionInfo = new FramelessFunctionInfo();
     $framelessFunctionInfo->arity = $json["arity"];
+    $framelessFunctionInfo->needsArgCopy = $json["needs_arg_copy"] ?? false;
     return $framelessFunctionInfo;
 }
 
diff --git a/ext/opcache/jit/zend_jit.c b/ext/opcache/jit/zend_jit.c
index da73c98c4355..dd65d9c7bc1b 100644
--- a/ext/opcache/jit/zend_jit.c
+++ b/ext/opcache/jit/zend_jit.c
@@ -2551,15 +2551,24 @@ static int zend_jit(const zend_op_array *op_array, zend_ssa *ssa, const zend_op
 						jit_frameless_icall0(jit, opline);
 						goto done;
 					case ZEND_FRAMELESS_ICALL_1:
+						if (ZEND_FLF_USES_ARG_COPY(opline)) {
+							break;
+						}
 						op1_info = OP1_INFO();
 						jit_frameless_icall1(jit, opline, op1_info);
 						goto done;
 					case ZEND_FRAMELESS_ICALL_2:
+						if (ZEND_FLF_USES_ARG_COPY(opline)) {
+							break;
+						}
 						op1_info = OP1_INFO();
 						op2_info = OP2_INFO();
 						jit_frameless_icall2(jit, opline, op1_info, op2_info);
 						goto done;
 					case ZEND_FRAMELESS_ICALL_3:
+						if (ZEND_FLF_USES_ARG_COPY(opline)) {
+							break;
+						}
 						op1_info = OP1_INFO();
 						op2_info = OP2_INFO();
 						jit_frameless_icall3(jit, opline, op1_info, op2_info, OP1_DATA_INFO());
diff --git a/ext/opcache/jit/zend_jit_trace.c b/ext/opcache/jit/zend_jit_trace.c
index 320967419055..1a15823d9959 100644
--- a/ext/opcache/jit/zend_jit_trace.c
+++ b/ext/opcache/jit/zend_jit_trace.c
@@ -6382,15 +6382,24 @@ static const void *zend_jit_trace(zend_jit_trace_rec *trace_buffer, uint32_t par
 						jit_frameless_icall0(jit, opline);
 						goto done;
 					case ZEND_FRAMELESS_ICALL_1:
+						if (ZEND_FLF_USES_ARG_COPY(opline)) {
+							break;
+						}
 						op1_info = OP1_INFO();
 						jit_frameless_icall1(jit, opline, op1_info);
 						goto done;
 					case ZEND_FRAMELESS_ICALL_2:
+						if (ZEND_FLF_USES_ARG_COPY(opline)) {
+							break;
+						}
 						op1_info = OP1_INFO();
 						op2_info = OP2_INFO();
 						jit_frameless_icall2(jit, opline, op1_info, op2_info);
 						goto done;
 					case ZEND_FRAMELESS_ICALL_3:
+						if (ZEND_FLF_USES_ARG_COPY(opline)) {
+							break;
+						}
 						op1_info = OP1_INFO();
 						op2_info = OP2_INFO();
 						jit_frameless_icall3(jit, opline, op1_info, op2_info, OP1_DATA_INFO());
diff --git a/ext/pcre/php_pcre.stub.php b/ext/pcre/php_pcre.stub.php
index 0cd045b7efae..2e8e61ad95df 100644
--- a/ext/pcre/php_pcre.stub.php
+++ b/ext/pcre/php_pcre.stub.php
@@ -100,7 +100,7 @@
 
 /**
  * @param array $matches
- * @frameless-function {"arity": 2}
+ * @frameless-function {"arity": 2, "needs_arg_copy": true}
  */
 function preg_match(string $pattern, string $subject, &$matches = null, int $flags = 0, int $offset = 0): int|false {}
 
@@ -110,7 +110,7 @@ function preg_match_all(string $pattern, string $subject, &$matches = null, int
 /**
  * @param int $count
  * @return string|array<int|string, string>|null
- * @frameless-function {"arity": 3}
+ * @frameless-function {"arity": 3, "needs_arg_copy": true}
  */
 function preg_replace(string|array $pattern, string|array $replacement, string|array $subject, int $limit = -1, &$count = null): string|array|null {}
 
diff --git a/ext/pcre/php_pcre_arginfo.h b/ext/pcre/php_pcre_arginfo.h
index 86eaf0d8d60f..1d9e0958df2e 100644
--- a/ext/pcre/php_pcre_arginfo.h
+++ b/ext/pcre/php_pcre_arginfo.h
@@ -1,5 +1,5 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: 63de1d37ab303e1d6af7c96eaeeba09d7f35d116 */
+ * Stub hash: a04e5cf44bf936f6e5122b7ca2526b98913df1c7 */
 
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_MASK_EX(arginfo_preg_match, 0, 2, MAY_BE_LONG|MAY_BE_FALSE)
 	ZEND_ARG_TYPE_INFO(0, pattern, IS_STRING, 0)
@@ -65,13 +65,13 @@ ZEND_END_ARG_INFO()
 
 ZEND_FRAMELESS_FUNCTION(preg_match, 2);
 static const zend_frameless_function_info frameless_function_infos_preg_match[] = {
-	{ ZEND_FRAMELESS_FUNCTION_NAME(preg_match, 2), 2 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(preg_match, 2), 2 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
 ZEND_FRAMELESS_FUNCTION(preg_replace, 3);
 static const zend_frameless_function_info frameless_function_infos_preg_replace[] = {
-	{ ZEND_FRAMELESS_FUNCTION_NAME(preg_replace, 3), 3 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(preg_replace, 3), 3 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
diff --git a/ext/pcre/tests/gh21639.phpt b/ext/pcre/tests/gh21639.phpt
new file mode 100644
index 000000000000..4a896e966d27
--- /dev/null
+++ b/ext/pcre/tests/gh21639.phpt
@@ -0,0 +1,29 @@
+--TEST--
+GH-21639: Frameless preg_replace keeps volatile arguments alive
+--EXTENSIONS--
+pcre
+--FILE--
+<?php
+class PregReplaceSubject {
+    public function __toString(): string {
+        global $pregReplaceSubject;
+
+        $pregReplaceSubject = null;
+
+        return "a";
+    }
+}
+
+$pregReplaceSubject = [new PregReplaceSubject(), "aa"];
+
+var_dump(preg_replace("/a/", "b", $pregReplaceSubject));
+var_dump($pregReplaceSubject);
+?>
+--EXPECT--
+array(2) {
+  [0]=>
+  string(1) "b"
+  [1]=>
+  string(2) "bb"
+}
+NULL
diff --git a/ext/standard/basic_functions.stub.php b/ext/standard/basic_functions.stub.php
index 091b5cbac22b..5a8d000d1368 100644
--- a/ext/standard/basic_functions.stub.php
+++ b/ext/standard/basic_functions.stub.php
@@ -1614,13 +1614,13 @@ function key(array|object $array): int|string|null {}
 
 /**
  * @compile-time-eval
- * @frameless-function {"arity": 2}
+ * @frameless-function {"arity": 2, "needs_arg_copy": true}
  */
 function min(mixed $value, mixed ...$values): mixed {}
 
 /**
  * @compile-time-eval
- * @frameless-function {"arity": 2}
+ * @frameless-function {"arity": 2, "needs_arg_copy": true}
  */
 function max(mixed $value, mixed ...$values): mixed {}
 
@@ -1630,8 +1630,8 @@ function array_walk_recursive(array|object &$array, callable $callback, mixed $a
 
 /**
  * @compile-time-eval
- * @frameless-function {"arity": 2}
- * @frameless-function {"arity": 3}
+ * @frameless-function {"arity": 2, "needs_arg_copy": true}
+ * @frameless-function {"arity": 3, "needs_arg_copy": true}
  */
 function in_array(mixed $needle, array $haystack, bool $strict = false): bool {}
 
@@ -2311,7 +2311,7 @@ function strcoll(string $string1, string $string2): int {}
 /**
  * @compile-time-eval
  * @frameless-function {"arity": 1}
- * @frameless-function {"arity": 2}
+ * @frameless-function {"arity": 2, "needs_arg_copy": true}
  */
 function trim(string $string, string $characters = " \n\r\t\v\0"): string {}
 
@@ -2339,8 +2339,8 @@ function explode(string $separator, string $string, int $limit = PHP_INT_MAX): a
 
 /**
  * @compile-time-eval
- * @frameless-function {"arity": 1}
- * @frameless-function {"arity": 2}
+ * @frameless-function {"arity": 1, "needs_arg_copy": true}
+ * @frameless-function {"arity": 2, "needs_arg_copy": true}
  */
 function implode(string|array $separator, ?array $array = null): string {}
 
@@ -2368,7 +2368,7 @@ function basename(string $path, string $suffix = ""): string {}
 /**
  * @refcount 1
  * @frameless-function {"arity": 1}
- * @frameless-function {"arity": 2}
+ * @frameless-function {"arity": 2, "needs_arg_copy": true}
  */
 function dirname(string $path, int $levels = 1): string {}
 
@@ -2387,8 +2387,8 @@ function stristr(string $haystack, string $needle, bool $before_needle = false):
 /**
  * @compile-time-eval
  * @refcount 1
- * @frameless-function {"arity": 2}
- * @frameless-function {"arity": 3}
+ * @frameless-function {"arity": 2, "needs_arg_copy": true}
+ * @frameless-function {"arity": 3, "needs_arg_copy": true}
  */
 function strstr(string $haystack, string $needle, bool $before_needle = false): string|false {}
 
@@ -2397,8 +2397,8 @@ function strchr(string $haystack, string $needle, bool $before_needle = false):
 
 /**
  * @compile-time-eval
- * @frameless-function {"arity": 2}
- * @frameless-function {"arity": 3}
+ * @frameless-function {"arity": 2, "needs_arg_copy": true}
+ * @frameless-function {"arity": 3, "needs_arg_copy": true}
  */
 function strpos(string $haystack, string $needle, int $offset = 0): int|false {}
 
@@ -2419,13 +2419,13 @@ function strrchr(string $haystack, string $needle, bool $before_needle = false):
 
 /**
  * @compile-time-eval
- * @frameless-function {"arity": 2}
+ * @frameless-function {"arity": 2, "needs_arg_copy": true}
  */
 function str_contains(string $haystack, string $needle): bool {}
 
 /**
  * @compile-time-eval
- * @frameless-function {"arity": 2}
+ * @frameless-function {"arity": 2, "needs_arg_copy": true}
  */
 function str_starts_with(string $haystack, string $needle): bool {}
 
@@ -2440,8 +2440,8 @@ function chunk_split(string $string, int $length = 76, string $separator = "\r\n
 
 /**
  * @compile-time-eval
- * @frameless-function {"arity": 2}
- * @frameless-function {"arity": 3}
+ * @frameless-function {"arity": 2, "needs_arg_copy": true}
+ * @frameless-function {"arity": 3, "needs_arg_copy": true}
  */
 function substr(string $string, int $offset, ?int $length = null): string {}
 
@@ -2480,8 +2480,8 @@ function ucwords(string $string, string $separators = " \t\r\n\f\v"): string {}
 
 /**
  * @compile-time-eval
- * @frameless-function {"arity": 2}
- * @frameless-function {"arity": 3}
+ * @frameless-function {"arity": 2, "needs_arg_copy": true}
+ * @frameless-function {"arity": 3, "needs_arg_copy": true}
  */
 function strtr(string $string, string|array $from, ?string $to = null): string {}
 
@@ -2520,7 +2520,7 @@ function stripslashes(string $string): string {}
  * @param int $count
  * @return string|array<int|string, string>
  * @compile-time-eval
- * @frameless-function {"arity": 3}
+ * @frameless-function {"arity": 3, "needs_arg_copy": true}
  */
 function str_replace(array|string $search, array|string $replace, string|array $subject, &$count = null): string|array {}
 
diff --git a/ext/standard/basic_functions_arginfo.h b/ext/standard/basic_functions_arginfo.h
index 666957db7120..8c0652186132 100644
--- a/ext/standard/basic_functions_arginfo.h
+++ b/ext/standard/basic_functions_arginfo.h
@@ -1,5 +1,5 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: 5eeeaf1f292c72e4553dabc5a64f27781bf57d86 */
+ * Stub hash: e9a00a008a50c21542a4daf8e99e2cf7332be0e4 */
 
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_set_time_limit, 0, 1, _IS_BOOL, 0)
 	ZEND_ARG_TYPE_INFO(0, seconds, IS_LONG, 0)
@@ -2183,21 +2183,21 @@ ZEND_END_ARG_INFO()
 
 ZEND_FRAMELESS_FUNCTION(min, 2);
 static const zend_frameless_function_info frameless_function_infos_min[] = {
-	{ ZEND_FRAMELESS_FUNCTION_NAME(min, 2), 2 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(min, 2), 2 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
 ZEND_FRAMELESS_FUNCTION(max, 2);
 static const zend_frameless_function_info frameless_function_infos_max[] = {
-	{ ZEND_FRAMELESS_FUNCTION_NAME(max, 2), 2 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(max, 2), 2 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
 ZEND_FRAMELESS_FUNCTION(in_array, 2);
 ZEND_FRAMELESS_FUNCTION(in_array, 3);
 static const zend_frameless_function_info frameless_function_infos_in_array[] = {
-	{ ZEND_FRAMELESS_FUNCTION_NAME(in_array, 2), 2 },
-	{ ZEND_FRAMELESS_FUNCTION_NAME(in_array, 3), 3 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(in_array, 2), 2 | ZEND_FLF_ARG_COPY },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(in_array, 3), 3 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
@@ -2205,15 +2205,15 @@ ZEND_FRAMELESS_FUNCTION(trim, 1);
 ZEND_FRAMELESS_FUNCTION(trim, 2);
 static const zend_frameless_function_info frameless_function_infos_trim[] = {
 	{ ZEND_FRAMELESS_FUNCTION_NAME(trim, 1), 1 },
-	{ ZEND_FRAMELESS_FUNCTION_NAME(trim, 2), 2 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(trim, 2), 2 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
 ZEND_FRAMELESS_FUNCTION(implode, 1);
 ZEND_FRAMELESS_FUNCTION(implode, 2);
 static const zend_frameless_function_info frameless_function_infos_implode[] = {
-	{ ZEND_FRAMELESS_FUNCTION_NAME(implode, 1), 1 },
-	{ ZEND_FRAMELESS_FUNCTION_NAME(implode, 2), 2 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(implode, 1), 1 | ZEND_FLF_ARG_COPY },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(implode, 2), 2 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
@@ -2221,57 +2221,57 @@ ZEND_FRAMELESS_FUNCTION(dirname, 1);
 ZEND_FRAMELESS_FUNCTION(dirname, 2);
 static const zend_frameless_function_info frameless_function_infos_dirname[] = {
 	{ ZEND_FRAMELESS_FUNCTION_NAME(dirname, 1), 1 },
-	{ ZEND_FRAMELESS_FUNCTION_NAME(dirname, 2), 2 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(dirname, 2), 2 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
 ZEND_FRAMELESS_FUNCTION(strstr, 2);
 ZEND_FRAMELESS_FUNCTION(strstr, 3);
 static const zend_frameless_function_info frameless_function_infos_strstr[] = {
-	{ ZEND_FRAMELESS_FUNCTION_NAME(strstr, 2), 2 },
-	{ ZEND_FRAMELESS_FUNCTION_NAME(strstr, 3), 3 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(strstr, 2), 2 | ZEND_FLF_ARG_COPY },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(strstr, 3), 3 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
 ZEND_FRAMELESS_FUNCTION(strpos, 2);
 ZEND_FRAMELESS_FUNCTION(strpos, 3);
 static const zend_frameless_function_info frameless_function_infos_strpos[] = {
-	{ ZEND_FRAMELESS_FUNCTION_NAME(strpos, 2), 2 },
-	{ ZEND_FRAMELESS_FUNCTION_NAME(strpos, 3), 3 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(strpos, 2), 2 | ZEND_FLF_ARG_COPY },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(strpos, 3), 3 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
 ZEND_FRAMELESS_FUNCTION(str_contains, 2);
 static const zend_frameless_function_info frameless_function_infos_str_contains[] = {
-	{ ZEND_FRAMELESS_FUNCTION_NAME(str_contains, 2), 2 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(str_contains, 2), 2 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
 ZEND_FRAMELESS_FUNCTION(str_starts_with, 2);
 static const zend_frameless_function_info frameless_function_infos_str_starts_with[] = {
-	{ ZEND_FRAMELESS_FUNCTION_NAME(str_starts_with, 2), 2 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(str_starts_with, 2), 2 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
 ZEND_FRAMELESS_FUNCTION(substr, 2);
 ZEND_FRAMELESS_FUNCTION(substr, 3);
 static const zend_frameless_function_info frameless_function_infos_substr[] = {
-	{ ZEND_FRAMELESS_FUNCTION_NAME(substr, 2), 2 },
-	{ ZEND_FRAMELESS_FUNCTION_NAME(substr, 3), 3 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(substr, 2), 2 | ZEND_FLF_ARG_COPY },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(substr, 3), 3 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
 ZEND_FRAMELESS_FUNCTION(strtr, 2);
 ZEND_FRAMELESS_FUNCTION(strtr, 3);
 static const zend_frameless_function_info frameless_function_infos_strtr[] = {
-	{ ZEND_FRAMELESS_FUNCTION_NAME(strtr, 2), 2 },
-	{ ZEND_FRAMELESS_FUNCTION_NAME(strtr, 3), 3 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(strtr, 2), 2 | ZEND_FLF_ARG_COPY },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(strtr, 3), 3 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };
 
 ZEND_FRAMELESS_FUNCTION(str_replace, 3);
 static const zend_frameless_function_info frameless_function_infos_str_replace[] = {
-	{ ZEND_FRAMELESS_FUNCTION_NAME(str_replace, 3), 3 },
+	{ ZEND_FRAMELESS_FUNCTION_NAME(str_replace, 3), 3 | ZEND_FLF_ARG_COPY },
 	{ 0 },
 };