Index: lib/lsan/lsan_common.h
===================================================================
--- lib/lsan/lsan_common.h
+++ lib/lsan/lsan_common.h
@@ -118,6 +118,10 @@
 void InitializePlatformSpecificModules();
 void ProcessGlobalRegions(Frontier *frontier);
 void ProcessPlatformSpecificAllocations(Frontier *frontier);
+void ProcessPlatformSpecificRootRegion(Frontier *frontier, uptr root_begin,
+                                       uptr root_end);
+void ScanRootRegion(Frontier *frontier, uptr root_begin, uptr root_end,
+                    uptr region_begin, uptr region_end, uptr prot);
 // Run stoptheworld while holding any platform-specific locks.
 void DoStopTheWorld(StopTheWorldCallback callback, void* argument);
 
Index: lib/lsan/lsan_common.cc
===================================================================
--- lib/lsan/lsan_common.cc
+++ lib/lsan/lsan_common.cc
@@ -291,6 +291,20 @@
   }
 }
 
+void ScanRootRegion(Frontier *frontier, uptr root_begin, uptr root_end,
+                         uptr region_begin, uptr region_end, uptr prot) {
+    uptr intersection_begin = Max(root_begin, region_begin);
+    uptr intersection_end = Min(region_end, root_end);
+    if (intersection_begin >= intersection_end) return;
+    bool is_readable = prot & MemoryMappingLayout::kProtectionRead;
+    LOG_POINTERS("Root region %p-%p intersects with mapped region %p-%p (%s)\n",
+                 root_begin, root_end, region_begin, region_end,
+                 is_readable ? "readable" : "unreadable");
+    if (is_readable)
+      ScanRangeForPointers(intersection_begin, intersection_end, frontier,
+                           "ROOT", kReachable);
+}
+
 static void ProcessRootRegion(Frontier *frontier, uptr root_begin,
                               uptr root_end) {
   MemoryMappingLayout proc_maps(/*cache_enabled*/true);
@@ -298,17 +312,9 @@
   while (proc_maps.Next(&begin, &end,
                         /*offset*/ nullptr, /*filename*/ nullptr,
                         /*filename_size*/ 0, &prot)) {
-    uptr intersection_begin = Max(root_begin, begin);
-    uptr intersection_end = Min(end, root_end);
-    if (intersection_begin >= intersection_end) continue;
-    bool is_readable = prot & MemoryMappingLayout::kProtectionRead;
-    LOG_POINTERS("Root region %p-%p intersects with mapped region %p-%p (%s)\n",
-                 root_begin, root_end, begin, end,
-                 is_readable ? "readable" : "unreadable");
-    if (is_readable)
-      ScanRangeForPointers(intersection_begin, intersection_end, frontier,
-                           "ROOT", kReachable);
+    ScanRootRegion(frontier, root_begin, root_end, begin, end, prot);
   }
+  ProcessPlatformSpecificRootRegion(frontier, root_begin, root_end);
 }
 
 // Scans root regions for heap pointers.
Index: lib/lsan/lsan_common_linux.cc
===================================================================
--- lib/lsan/lsan_common_linux.cc
+++ lib/lsan/lsan_common_linux.cc
@@ -91,6 +91,9 @@
 
 LoadedModule *GetLinker() { return linker; }
 
+void ProcessPlatformSpecificRootRegion(Frontier *frontier, uptr root_begin,
+                                       uptr root_end) {}
+
 void ProcessPlatformSpecificAllocations(Frontier *frontier) {}
 
 struct DoStopTheWorldParam {
Index: lib/lsan/lsan_common_mac.cc
===================================================================
--- lib/lsan/lsan_common_mac.cc
+++ lib/lsan/lsan_common_mac.cc
@@ -117,9 +117,24 @@
   }
 }
 
-// libxpc stashes some pointers in the Kernel Alloc Once page,
-// make sure not to report those as leaks.
-void ProcessPlatformSpecificAllocations(Frontier *frontier) {
+typedef void (*MemoryRegionCallback)(Frontier *frontier, uptr address,
+                                     uptr size, vm_region_submap_info_64 &info,
+                                     void *arg);
+
+typedef struct {
+  uptr root_begin;
+  uptr root_end;
+} root_region_arg_t;
+
+void ScanRootRegionCb(Frontier *frontier, uptr address, uptr size,
+                      vm_region_submap_info_64 &info, void *arg) {
+  root_region_arg_t *data = reinterpret_cast<root_region_arg_t *>(arg);
+  ScanRootRegion(frontier, data->root_begin, data->root_end, address,
+                 address+size, info.protection);
+}
+
+static void ProcessMemoryRegion(Frontier *frontier,
+                                MemoryRegionCallback callback, void *arg) {
   mach_port_name_t port;
   if (task_for_pid(mach_task_self(), internal_getpid(), &port)
       != KERN_SUCCESS) {
@@ -136,15 +151,33 @@
     struct vm_region_submap_info_64 info;
     err = vm_region_recurse_64(port, &address, &size, &depth,
                                (vm_region_info_t)&info, &count);
-    if (info.user_tag == VM_MEMORY_OS_ALLOC_ONCE) {
-      ScanRangeForPointers(address, address + size, frontier,
-                           "GLOBAL", kReachable);
-      return;
-    }
+    callback(frontier, address, size, info, arg);
     address += size;
   }
 }
 
+void ProcessPlatformSpecificRootRegion(Frontier *frontier, uptr root_begin,
+                                       uptr root_end) {
+  root_region_arg_t arg;
+  arg.root_begin = root_begin;
+  arg.root_end = root_end;
+  ProcessMemoryRegion(frontier, ScanRootRegionCb, &arg);
+}
+
+void AllocOncePageCb(Frontier *frontier, uptr address, uptr size,
+                     vm_region_submap_info_64 &info, void *arg) {
+  if (info.user_tag == VM_MEMORY_OS_ALLOC_ONCE) {
+    ScanRangeForPointers(address, address + size, frontier,
+                         "GLOBAL", kReachable);
+  }
+}
+
+// libxpc stashes some pointers in the Kernel Alloc Once page,
+// make sure not to report those as leaks.
+void ProcessPlatformSpecificAllocations(Frontier *frontier) {
+  ProcessMemoryRegion(frontier, AllocOncePageCb, nullptr);
+}
+
 void DoStopTheWorld(StopTheWorldCallback callback, void *argument) {
   StopTheWorld(callback, argument);
 }