Index: lib/sanitizer_common/sanitizer_allocator_combined.h
===================================================================
--- lib/sanitizer_common/sanitizer_allocator_combined.h
+++ lib/sanitizer_common/sanitizer_allocator_combined.h
@@ -49,18 +49,19 @@
       size = 1;
     if (size + alignment < size) return ReturnNullOrDieOnBadRequest();
     if (check_rss_limit && RssLimitIsExceeded()) return ReturnNullOrDieOnOOM();
+    uptr rounded_size = size;
     if (alignment > 8)
-      size = RoundUpTo(size, alignment);
+      rounded_size = RoundUpTo(rounded_size, alignment);
     void *res;
-    bool from_primary = primary_.CanAllocate(size, alignment);
+    bool from_primary = primary_.CanAllocate(rounded_size, alignment);
     if (from_primary)
-      res = cache->Allocate(&primary_, primary_.ClassID(size));
+      res = cache->Allocate(&primary_, primary_.ClassID(rounded_size));
     else
       res = secondary_.Allocate(&stats_, size, alignment);
     if (alignment > 8)
       CHECK_EQ(reinterpret_cast<uptr>(res) & (alignment - 1), 0);
     if (cleared && res && from_primary)
-      internal_bzero_aligned16(res, RoundUpTo(size, 16));
+      internal_bzero_aligned16(res, RoundUpTo(rounded_size, 16));
     return res;
   }
 
Index: lib/scudo/scudo_allocator_secondary.h
===================================================================
--- lib/scudo/scudo_allocator_secondary.h
+++ lib/scudo/scudo_allocator_secondary.h
@@ -46,7 +46,7 @@
     uptr UserBeg = MapBeg + PageSize + HeadersSize;
     // In the event of larger alignments, we will attempt to fit the mmap area
     // better and unmap extraneous memory. This will also ensure that the
-    // offset field of the header stays small (it will always be 0).
+    // offset and unused bytes field of the header stay small.
     if (Alignment > MinAlignment) {
       if (UserBeg & (Alignment - 1))
         UserBeg += Alignment - (UserBeg & (Alignment - 1));
@@ -54,8 +54,9 @@
       uptr NewMapBeg = UserBeg - HeadersSize;
       NewMapBeg = RoundDownTo(NewMapBeg, PageSize) - PageSize;
       CHECK_GE(NewMapBeg, MapBeg);
-      uptr NewMapSize = RoundUpTo(MapSize - Alignment, PageSize);
-      uptr NewMapEnd = NewMapBeg + NewMapSize;
+      uptr NewMapEnd =
+          RoundUpTo(UserBeg + Size - Alignment - AlignedChunkHeaderSize,
+                    PageSize) + PageSize;
       CHECK_LE(NewMapEnd, MapEnd);
       // Unmap the extra memory if it's large enough.
       uptr Diff = NewMapBeg - MapBeg;
@@ -65,8 +66,8 @@
       if (Diff > PageSize)
         UnmapOrDie(reinterpret_cast<void *>(NewMapEnd), Diff);
       MapBeg = NewMapBeg;
-      MapSize = NewMapSize;
       MapEnd = NewMapEnd;
+      MapSize = NewMapEnd - NewMapBeg;
     }
     uptr UserEnd = UserBeg - AlignedChunkHeaderSize + Size;
     // For larger alignments, Alignment was added by the frontend to Size.
Index: lib/scudo/scudo_utils.cpp
===================================================================
--- lib/scudo/scudo_utils.cpp
+++ lib/scudo/scudo_utils.cpp
@@ -17,7 +17,9 @@
 #include <fcntl.h>
 #include <stdarg.h>
 #include <unistd.h>
-#include <cpuid.h>
+#if defined(__x86_64__) || defined(__i386__)
+# include <cpuid.h>
+#endif
 
 #include <cstring>