--- a/memory/build/mozjemalloc.cpp
+++ b/memory/build/mozjemalloc.cpp
@@ -2805,18 +2805,22 @@ void* arena_t::MallocSmall(size_t aSize,
     if (MOZ_UNLIKELY(mRandomizeSmallAllocations && mPRNG == nullptr)) {
       // This is frustrating. Because the code backing RandomUint64 (arc4random
       // for example) may allocate memory, and because
       // mRandomizeSmallAllocations is true and we haven't yet initilized mPRNG,
       // we would re-enter this same case and cause a deadlock inside e.g.
       // arc4random.  So we temporarily disable mRandomizeSmallAllocations to
       // skip this case and then re-enable it
       mRandomizeSmallAllocations = false;
-      mozilla::Maybe<uint64_t> prngState1 = mozilla::RandomUint64();
-      mozilla::Maybe<uint64_t> prngState2 = mozilla::RandomUint64();
+      mozilla::Maybe<uint64_t> prngState1, prngState2;
+      {
+        mozilla::recordreplay::AutoEnsurePassThroughThreadEvents pt;
+        prngState1 = mozilla::RandomUint64();
+        prngState2 = mozilla::RandomUint64();
+      }
       void* backing =
           base_alloc(sizeof(mozilla::non_crypto::XorShift128PlusRNG));
       mPRNG = new (backing) mozilla::non_crypto::XorShift128PlusRNG(
           prngState1.valueOr(0), prngState2.valueOr(0));
       mRandomizeSmallAllocations = true;
     }
 
     MutexAutoLock lock(mLock);
@@ -3537,17 +3541,21 @@ arena_t* ArenaCollection::CreateArena(bo
   }
 
   // For private arenas, generate a cryptographically-secure random id for the
   // new arena. If an attacker manages to get control of the process, this
   // should make it more difficult for them to "guess" the ID of a memory
   // arena, stopping them from getting data they may want
 
   while (true) {
-    mozilla::Maybe<uint64_t> maybeRandomId = mozilla::RandomUint64();
+    mozilla::Maybe<uint64_t> maybeRandomId;
+    {
+      mozilla::recordreplay::AutoEnsurePassThroughThreadEvents pt;
+      maybeRandomId = mozilla::RandomUint64();
+    }
     MOZ_RELEASE_ASSERT(maybeRandomId.isSome());
 
     // Keep looping until we ensure that the random number we just generated
     // isn't already in use by another active arena
     arena_t* existingArena =
         GetByIdInternal(maybeRandomId.value(), true /*aIsPrivate*/);
 
     if (!existingArena) {

--- a/memory/replace/logalloc/replay/moz.build
+++ b/memory/replace/logalloc/replay/moz.build
@@ -5,16 +5,17 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 Program('logalloc-replay')
 
 SOURCES += [
     '/mfbt/Assertions.cpp',
     '/mfbt/Poison.cpp',
     '/mfbt/RandomNum.cpp',
+    '/mfbt/RecordReplay.cpp',
     '/mfbt/TaggedAnonymousMemory.cpp',
     '/mfbt/Unused.cpp',
     'Replay.cpp',
 ]
 
 if CONFIG['MOZ_REPLACE_MALLOC_STATIC'] and \
    (CONFIG['MOZ_DMD'] or CONFIG['MOZ_PHC']):
     UNIFIED_SOURCES += [