diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_allocator.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_allocator.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_allocator.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_allocator.cpp
@@ -145,7 +145,8 @@
   // Align allocation size.
   size = RoundUpTo(size, low_level_alloc_min_alignment);
   if (allocated_end_ - allocated_current_ < (sptr)size) {
-    uptr size_to_allocate = RoundUpTo(size, GetPageSizeCached());
+    uptr size_to_allocate = RoundUpTo(
+        size, GetPageSizeCached() * SANITIZER_LOW_LEVEL_ALLOCATOR_NUM_PAGES);
     allocated_current_ = (char *)MmapOrDie(size_to_allocate, __func__);
     allocated_end_ = allocated_current_ + size_to_allocate;
     if (low_level_alloc_callback) {
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h b/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h
--- a/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h
@@ -86,6 +86,17 @@
 // And then use it as: if (compare_hook) compare_hook(a, b);
 //----------------------------------------------------------------------------//
 
+// This defines the minimum number of pages the LowLevelAllocator will mmap when
+// it needs more space for an allocation. Increasing this will reduce
+// fragmentation for heavily used LowLevelAllocators but less space-efficient
+// for allocators used a few times.
+#ifndef SANITIZER_LOW_LEVEL_ALLOCATOR_NUM_PAGES
+#  if SANITIZER_FUCHSIA
+#    define SANITIZER_LOW_LEVEL_ALLOCATOR_NUM_PAGES 16
+#  else
+#    define SANITIZER_LOW_LEVEL_ALLOCATOR_NUM_PAGES 1
+#  endif
+#endif  // defined(SANITIZER_LOW_LEVEL_ALLOCATOR_NUM_PAGES)
 
 // We can use .preinit_array section on Linux to call sanitizer initialization
 // functions very early in the process startup (unless PIC macro is defined).