diff --git a/Libraries/LibIPC/Forward.h b/Libraries/LibIPC/Forward.h
index 30c28bc192a..06e2678cd9c 100644
--- a/Libraries/LibIPC/Forward.h
+++ b/Libraries/LibIPC/Forward.h
@@ -10,6 +10,7 @@
 
 namespace IPC {
 
+class AutoCloseFileDescriptor;
 class Decoder;
 class Encoder;
 class Message;
@@ -23,4 +24,7 @@ ErrorOr<void> encode(Encoder&, T const&);
 template<typename T>
 ErrorOr<T> decode(Decoder&);
 
+using MessageDataType = Vector<u8, 1024>;
+using MessageFileType = Vector<NonnullRefPtr<AutoCloseFileDescriptor>, 1>;
+
 }
diff --git a/Libraries/LibIPC/Message.cpp b/Libraries/LibIPC/Message.cpp
index 680cc329d08..864250f6d6f 100644
--- a/Libraries/LibIPC/Message.cpp
+++ b/Libraries/LibIPC/Message.cpp
@@ -35,6 +35,13 @@ ErrorOr<void> MessageBuffer::append_file_descriptor(int fd)
     return {};
 }
 
+ErrorOr<void> MessageBuffer::extend(MessageBuffer&& buffer)
+{
+    TRY(m_data.try_extend(move(buffer.m_data)));
+    TRY(m_fds.try_extend(move(buffer.m_fds)));
+    return {};
+}
+
 ErrorOr<void> MessageBuffer::transfer_message(Transport& transport)
 {
     Checked<MessageSizeType> checked_message_size { m_data.size() };
diff --git a/Libraries/LibIPC/Message.h b/Libraries/LibIPC/Message.h
index c0cc534219e..7ecce67c818 100644
--- a/Libraries/LibIPC/Message.h
+++ b/Libraries/LibIPC/Message.h
@@ -10,6 +10,7 @@
 #include <AK/Error.h>
 #include <AK/Vector.h>
 #include <LibIPC/AutoCloseFileDescriptor.h>
+#include <LibIPC/Forward.h>
 #include <LibIPC/Transport.h>
 
 namespace IPC {
@@ -18,7 +19,7 @@ class MessageBuffer {
 public:
     MessageBuffer();
 
-    MessageBuffer(Vector<u8, 1024> data, Vector<NonnullRefPtr<AutoCloseFileDescriptor>, 1> fds)
+    MessageBuffer(MessageDataType data, MessageFileType fds)
         : m_data(move(data))
         , m_fds(move(fds))
     {
@@ -29,14 +30,19 @@ public:
 
     ErrorOr<void> append_file_descriptor(int fd);
 
+    ErrorOr<void> extend(MessageBuffer&& buffer);
+
     ErrorOr<void> transfer_message(Transport& transport);
 
-    auto const& data() const { return m_data; }
-    auto take_fds() { return move(m_fds); }
+    MessageDataType const& data() const { return m_data; }
+    MessageDataType take_data() { return move(m_data); }
+
+    MessageFileType const& fds() const { return m_fds; }
+    MessageFileType take_fds() { return move(m_fds); }
 
 private:
-    Vector<u8, 1024> m_data;
-    Vector<NonnullRefPtr<AutoCloseFileDescriptor>, 1> m_fds;
+    MessageDataType m_data;
+    MessageFileType m_fds;
 #ifdef AK_OS_WINDOWS
     Vector<size_t> m_handle_offsets;
 #endif
diff --git a/Libraries/LibIPC/MessageWindows.cpp b/Libraries/LibIPC/MessageWindows.cpp
index 3eb3dbc7197..c5be237c534 100644
--- a/Libraries/LibIPC/MessageWindows.cpp
+++ b/Libraries/LibIPC/MessageWindows.cpp
@@ -55,6 +55,14 @@ ErrorOr<void> MessageBuffer::append_file_descriptor(int handle)
     return {};
 }
 
+ErrorOr<void> MessageBuffer::extend(MessageBuffer&& buffer)
+{
+    TRY(m_data.try_extend(move(buffer.m_data)));
+    TRY(m_fds.try_extend(move(buffer.m_fds)));
+    TRY(m_handle_offsets.try_extend(move(buffer.m_handle_offsets)));
+    return {};
+}
+
 ErrorOr<void> MessageBuffer::transfer_message(Transport& transport)
 {
     Checked<MessageSizeType> checked_message_size { m_data.size() };