diff --git a/Userland/Libraries/LibJS/Bytecode/Op.h b/Userland/Libraries/LibJS/Bytecode/Op.h
index 7d98a9484f..633febe80e 100644
--- a/Userland/Libraries/LibJS/Bytecode/Op.h
+++ b/Userland/Libraries/LibJS/Bytecode/Op.h
@@ -1047,6 +1047,8 @@ public:
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
     DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
 
+    ScopeNode const& scope_node() const { return m_scope_node; }
+
 private:
     ScopeNode const& m_scope_node;
 };
diff --git a/Userland/Libraries/LibJS/JIT/Compiler.cpp b/Userland/Libraries/LibJS/JIT/Compiler.cpp
index 68d2f8451b..6d704069a1 100644
--- a/Userland/Libraries/LibJS/JIT/Compiler.cpp
+++ b/Userland/Libraries/LibJS/JIT/Compiler.cpp
@@ -1162,6 +1162,22 @@ void Compiler::compile_concat_string(Bytecode::Op::ConcatString const& op)
     check_exception();
 }
 
+static void cxx_block_declaration_instantiation(VM& vm, ScopeNode const& scope_node)
+{
+    auto old_environment = vm.running_execution_context().lexical_environment;
+    vm.bytecode_interpreter().saved_lexical_environment_stack().append(old_environment);
+    vm.running_execution_context().lexical_environment = new_declarative_environment(*old_environment);
+    scope_node.block_declaration_instantiation(vm, vm.running_execution_context().lexical_environment);
+}
+
+void Compiler::compile_block_declaration_instantiation(Bytecode::Op::BlockDeclarationInstantiation const& op)
+{
+    m_assembler.mov(
+        Assembler::Operand::Register(ARG1),
+        Assembler::Operand::Imm(bit_cast<u64>(&op.scope_node())));
+    native_call((void*)cxx_block_declaration_instantiation);
+}
+
 void Compiler::jump_to_exit()
 {
     m_assembler.jump(m_exit_label);
diff --git a/Userland/Libraries/LibJS/JIT/Compiler.h b/Userland/Libraries/LibJS/JIT/Compiler.h
index ec0dbc2324..bb6d1d17f3 100644
--- a/Userland/Libraries/LibJS/JIT/Compiler.h
+++ b/Userland/Libraries/LibJS/JIT/Compiler.h
@@ -103,7 +103,8 @@ private:
         O(TypeofVariable, typeof_variable)                                       \
         O(SetVariable, set_variable)                                             \
         O(ContinuePendingUnwind, continue_pending_unwind)                        \
-        O(ConcatString, concat_string)
+        O(ConcatString, concat_string)                                           \
+        O(BlockDeclarationInstantiation, block_declaration_instantiation)
 
 #    define DECLARE_COMPILE_OP(OpTitleCase, op_snake_case) \
         void compile_##op_snake_case(Bytecode::Op::OpTitleCase const&);