diff --git a/js/src/vm/HelperThreads.cpp b/js/src/vm/HelperThreads.cpp
index e33a10ffefd..bcd75cc8234 100644
--- a/js/src/vm/HelperThreads.cpp
+++ b/js/src/vm/HelperThreads.cpp
@@ -434,8 +434,26 @@ js::EnqueuePendingParseTasksAfterGC(JSRuntime* rt)
     HelperThreadState().notifyAll(GlobalHelperThreadState::PRODUCER);
 }
 
-static const uint32_t HELPER_STACK_SIZE = 512 * 1024;
-static const uint32_t HELPER_STACK_QUOTA = 450 * 1024;
+static const uint32_t kDefaultHelperStackSize = 512 * 1024;
+static const uint32_t kDefaultHelperStackQuota = 450 * 1024;
+
+// TSan enforces a minimum stack size that's just slightly larger than our
+// default helper stack size.  It does this to store blobs of TSan-specific
+// data on each thread's stack.  Unfortunately, that means that even though
+// we'll actually receive a larger stack than we requested, the effective
+// usable space of that stack is significantly less than what we expect.
+// To offset TSan stealing our stack space from underneath us, double the
+// default.
+//
+// Note that we don't need this for ASan/MOZ_ASAN because ASan doesn't
+// require all the thread-specific state that TSan does.
+#if defined(MOZ_TSAN)
+static const uint32_t HELPER_STACK_SIZE = 2 * kDefaultHelperStackSize;
+static const uint32_t HELPER_STACK_QUOTA = 2 * kDefaultHelperStackQuota;
+#else
+static const uint32_t HELPER_STACK_SIZE = kDefaultHelperStackSize;
+static const uint32_t HELPER_STACK_QUOTA = kDefaultHelperStackQuota;
+#endif
 
 void
 GlobalHelperThreadState::ensureInitialized()