diff --git a/OvmfPkg/Library/PlatformBdsLib/BdsPlatform.c b/OvmfPkg/Library/PlatformBdsLib/BdsPlatform.c
index 4a2f7f332d..0bc02baf03 100644
--- a/OvmfPkg/Library/PlatformBdsLib/BdsPlatform.c
+++ b/OvmfPkg/Library/PlatformBdsLib/BdsPlatform.c
@@ -13,6 +13,7 @@
 **/
 
 #include "BdsPlatform.h"
+#include <Guid/RootBridgesConnectedEventGroup.h>
 #include <Library/QemuBootOrderLib.h>
 
 
@@ -1244,6 +1245,11 @@ Returns:
   VisitAllInstancesOfProtocol (&gEfiPciRootBridgeIoProtocolGuid,
     ConnectRootBridge, NULL);
 
+  //
+  // Signal the ACPI platform driver that it can download QEMU ACPI tables.
+  //
+  EfiEventGroupSignal (&gRootBridgesConnectedEventGroupGuid);
+
   //
   // We can't signal End-of-Dxe earlier than this. Namely, End-of-Dxe triggers
   // the preparation of S3 system information. That logic has a hard dependency
diff --git a/OvmfPkg/Library/PlatformBdsLib/PlatformBdsLib.inf b/OvmfPkg/Library/PlatformBdsLib/PlatformBdsLib.inf
index ab5468368d..6a04b45803 100644
--- a/OvmfPkg/Library/PlatformBdsLib/PlatformBdsLib.inf
+++ b/OvmfPkg/Library/PlatformBdsLib/PlatformBdsLib.inf
@@ -70,3 +70,4 @@
 
 [Guids]
   gEfiEndOfDxeEventGroupGuid
+  gRootBridgesConnectedEventGroupGuid