Index: lib/asan/asan_mapping.h
===================================================================
--- lib/asan/asan_mapping.h
+++ lib/asan/asan_mapping.h
@@ -183,6 +183,7 @@
 #   define SHADOW_OFFSET kMIPS64_ShadowOffset64
 #  elif SANITIZER_WINDOWS64
 #   define SHADOW_OFFSET __asan_shadow_memory_dynamic_address
+#   define ASAN_DYNAMIC_SHADOW_ADDRESS 1
 #  else
 #   define SHADOW_OFFSET kDefaultShort64bitShadowOffset
 #  endif
Index: lib/asan/asan_rtl.cc
===================================================================
--- lib/asan/asan_rtl.cc
+++ lib/asan/asan_rtl.cc
@@ -463,16 +463,17 @@
 
   __asan_shadow_memory_dynamic_address = 0;
   uptr shadow_start = kLowShadowBeg;
-  if (shadow_start == 0) {
-    uptr granularity = GetMmapGranularity();
-    uptr alignment = 8 * granularity;
-    uptr left_padding = granularity;
-    uptr space_size = kHighShadowEnd + left_padding;
-
-    shadow_start = FindAvailableMemoryRange(space_size, alignment, granularity);
-    CHECK_NE((uptr)0, shadow_start);
-    CHECK(IsAligned(shadow_start, alignment));
-  }
+#if ASAN_DYNAMIC_SHADOW_ADDRESS
+  CHECK_EQ(0, shadow_start);
+  uptr granularity = GetMmapGranularity();
+  uptr alignment = 8 * granularity;
+  uptr left_padding = granularity;
+  uptr space_size = kHighShadowEnd + left_padding;
+
+  shadow_start = FindAvailableMemoryRange(space_size, alignment, granularity);
+  CHECK_NE((uptr)0, shadow_start);
+  CHECK(IsAligned(shadow_start, alignment));
+#endif
   __asan_shadow_memory_dynamic_address = shadow_start;
 
   if (kLowShadowBeg)