--- Source/WebKit/Platform/IPC/unix/IPCUtilitiesUnix.cpp.orig
+++ Source/WebKit/Platform/IPC/unix/IPCUtilitiesUnix.cpp
@@ -34,6 +34,18 @@
 SocketPair createPlatformConnection(int socketType, unsigned options)
 {
     std::array<int, 2> sockets;
+
+#if OS(DARWIN)
+    // macOS has a very small default buffer for AF_UNIX SOCK_DGRAM (2KB).
+    // WebKit IPC messages can be up to 4KB, so increase the buffer size.
+    socketType = SOCK_DGRAM;
+    RELEASE_ASSERT(socketpair(AF_UNIX, socketType, 0, sockets.data()) != -1);
+    constexpr int bufferSize = 262144;
+    setsockopt(sockets[0], SOL_SOCKET, SO_SNDBUF, &bufferSize, sizeof(bufferSize));
+    setsockopt(sockets[1], SOL_SOCKET, SO_SNDBUF, &bufferSize, sizeof(bufferSize));
+    setsockopt(sockets[0], SOL_SOCKET, SO_RCVBUF, &bufferSize, sizeof(bufferSize));
+    setsockopt(sockets[1], SOL_SOCKET, SO_RCVBUF, &bufferSize, sizeof(bufferSize));
+#else
 
 #if OS(LINUX)
     if ((options & SetCloexecOnServer) || (options & SetCloexecOnClient)) {
@@ -48,6 +60,7 @@
 #endif
 
     RELEASE_ASSERT(socketpair(AF_UNIX, socketType, 0, sockets.data()) != -1);
+#endif // OS(DARWIN)
 
     if (options & SetCloexecOnServer)
         RELEASE_ASSERT(setCloseOnExec(sockets[1]));