diff --git a/compiler-rt/lib/tsan/rtl/tsan_mman.cpp b/compiler-rt/lib/tsan/rtl/tsan_mman.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_mman.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_mman.cpp
@@ -379,6 +379,10 @@
 
 uptr user_alloc_usable_size_fast(const void *p) {
   MBlock *b = ctx->metamap.GetBlock((uptr)p);
+  // Static objects may have malloc'd before tsan completes
+  // initialization, and may believe returned ptrs to be valid.
+  if (!b)
+    return 0;  // Not a valid pointer.
   if (b->siz == 0)
     return 1;  // Zero-sized allocations are actually 1 byte.
   return b->siz;