diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp
@@ -1137,7 +1137,7 @@
   const uptr left_padding =
       Max<uptr>(granularity, 1ULL << min_shadow_base_alignment);
 
-  uptr space_size = shadow_size_bytes + left_padding;
+  uptr space_size = shadow_size_bytes;
 
   uptr largest_gap_found = 0;
   uptr max_occupied_addr = 0;
@@ -1162,7 +1162,7 @@
     }
     RestrictMemoryToMaxAddress(new_max_vm);
     high_mem_end = new_max_vm - 1;
-    space_size = (high_mem_end >> shadow_scale) + left_padding;
+    space_size = (high_mem_end >> shadow_scale);
     VReport(2, "FindDynamicShadowStart, space_size = %p\n", space_size);
     shadow_start = FindAvailableMemoryRange(space_size, alignment, left_padding,
                                             nullptr, nullptr);