diff --git a/gfx/ipc/GPUParent.cpp b/gfx/ipc/GPUParent.cpp
index caffad8e9b45..e4b3bfc57ca1 100644
--- a/gfx/ipc/GPUParent.cpp
+++ b/gfx/ipc/GPUParent.cpp
@@ -13,6 +13,7 @@
 #include "gfxPrefs.h"
 #include "GLContextProvider.h"
 #include "GPUProcessHost.h"
+#include "GPUProcessManager.h"
 #include "mozilla/Assertions.h"
 #include "mozilla/Telemetry.h"
 #include "mozilla/TimeStamp.h"
@@ -460,13 +461,30 @@ GPUParent::RecvNotifyGpuObservers(const nsCString& aTopic)
   return IPC_OK();
 }
 
+/* static */ void
+GPUParent::GetGPUProcessName(nsACString& aStr)
+{
+  auto processType = XRE_GetProcessType();
+  unsigned pid = 0;
+  if (processType == GeckoProcessType_GPU) {
+    pid = getpid();
+  } else {
+    MOZ_DIAGNOSTIC_ASSERT(processType == GeckoProcessType_Default);
+    pid = GPUProcessManager::Get()->GPUProcessPid();
+  }
+
+  nsPrintfCString processName("GPU (pid %u)", pid);
+  aStr.Assign(processName);
+}
+
 mozilla::ipc::IPCResult
 GPUParent::RecvRequestMemoryReport(const uint32_t& aGeneration,
                                    const bool& aAnonymize,
                                    const bool& aMinimizeMemoryUsage,
                                    const MaybeFileDesc& aDMDFile)
 {
-  nsPrintfCString processName("GPU (pid %u)", (unsigned)getpid());
+  nsAutoCString processName;
+  GetGPUProcessName(processName);
 
   mozilla::dom::MemoryReportRequestClient::Start(
     aGeneration, aAnonymize, aMinimizeMemoryUsage, aDMDFile, processName);
diff --git a/gfx/ipc/GPUParent.h b/gfx/ipc/GPUParent.h
index f0e864497111..6e05a5db9dbc 100644
--- a/gfx/ipc/GPUParent.h
+++ b/gfx/ipc/GPUParent.h
@@ -26,6 +26,11 @@ public:
 
   static GPUParent* GetSingleton();
 
+  // Gets the name of the GPU process, in the format expected by about:memory.
+  // There must be a GPU process active, and the caller must be either in that
+  // process or the parent process.
+  static void GetGPUProcessName(nsACString& aStr);
+
   bool Init(base::ProcessId aParentPid,
             const char* aParentBuildID,
             MessageLoop* aIOLoop,
diff --git a/gfx/thebes/gfxPlatform.cpp b/gfx/thebes/gfxPlatform.cpp
index 3ab4e46899b4..9f2d9fce65f7 100644
--- a/gfx/thebes/gfxPlatform.cpp
+++ b/gfx/thebes/gfxPlatform.cpp
@@ -663,8 +663,18 @@ struct WebRenderMemoryReporterHelper {
 
   void Report(size_t aBytes, const char* aName) const
   {
+    // Generally, memory reporters pass the empty string as the process name to
+    // indicate "current process". However, if we're using a GPU process, the
+    // measurements will actually take place in that process, and it's easier to
+    // just note that here rather than trying to invoke the memory reporter in
+    // the GPU process.
+    nsAutoCString processName;
+    if (gfxConfig::IsEnabled(Feature::GPU_PROCESS)) {
+      GPUParent::GetGPUProcessName(processName);
+    }
+
     nsPrintfCString path("explicit/gfx/webrender/%s", aName);
-    mCallback->Callback(EmptyCString(), path,
+    mCallback->Callback(processName, path,
                         nsIMemoryReporter::KIND_HEAP, nsIMemoryReporter::UNITS_BYTES,
                         aBytes, EmptyCString(), mData);
   }