Index: lib/sanitizer_common/sanitizer_common.h
===================================================================
--- lib/sanitizer_common/sanitizer_common.h
+++ lib/sanitizer_common/sanitizer_common.h
@@ -770,6 +770,7 @@
   ListOfModules() : modules_(kInitialCapacity) {}
   ~ListOfModules() { clear(); }
   void init();
+  void fallbackInit();
   const LoadedModule *begin() const { return modules_.begin(); }
   LoadedModule *begin() { return modules_.begin(); }
   const LoadedModule *end() const { return modules_.end(); }
Index: lib/sanitizer_common/sanitizer_linux_libcdep.cc
===================================================================
--- lib/sanitizer_common/sanitizer_linux_libcdep.cc
+++ lib/sanitizer_common/sanitizer_linux_libcdep.cc
@@ -25,6 +25,7 @@
 #include "sanitizer_placement_new.h"
 #include "sanitizer_procmaps.h"
 #include "sanitizer_stacktrace.h"
+#include "sanitizer_symbolizer.h"
 
 #include <dlfcn.h>  // for dlsym()
 #include <link.h>
@@ -457,6 +458,8 @@
     int (*)(struct dl_phdr_info *, size_t, void *), void *);
 #endif
 
+// When a custom loader is used, dl_iterate_phdr may not contain the full
+// list of modules. Allow callers to fall back to using procmaps.
 void ListOfModules::init() {
   clear();
 #if SANITIZER_ANDROID && __ANDROID_API__ <= 22
@@ -465,15 +468,20 @@
   // The runtime check allows the same library to work with
   // both K and L (and future) Android releases.
   if (api_level <= ANDROID_LOLLIPOP_MR1) { // L or earlier
-    MemoryMappingLayout memory_mapping(false);
-    memory_mapping.DumpListOfModules(&modules_);
-    return;
+    return fallbackInit();
   }
 #endif
+
   DlIteratePhdrData data = {&modules_, true};
   dl_iterate_phdr(dl_iterate_phdr_cb, &data);
 }
 
+void ListOfModules::fallbackInit() {
+  clear();
+  MemoryMappingLayout memory_mapping(false);
+  memory_mapping.DumpListOfModules(&modules_);
+}
+
 // getrusage does not give us the current RSS, only the max RSS.
 // Still, this is better than nothing if /proc/self/statm is not available
 // for some reason, e.g. due to a sandbox.
Index: lib/sanitizer_common/sanitizer_mac.cc
===================================================================
--- lib/sanitizer_common/sanitizer_mac.cc
+++ lib/sanitizer_common/sanitizer_mac.cc
@@ -415,6 +415,10 @@
   memory_mapping.DumpListOfModules(&modules_);
 }
 
+void ListOfModules::fallbackInit() {
+  init();
+}
+
 static HandleSignalMode GetHandleSignalModeImpl(int signum) {
   switch (signum) {
     case SIGABRT:
Index: lib/sanitizer_common/sanitizer_symbolizer.h
===================================================================
--- lib/sanitizer_common/sanitizer_symbolizer.h
+++ lib/sanitizer_common/sanitizer_symbolizer.h
@@ -119,6 +119,8 @@
   void AddHooks(StartSymbolizationHook start_hook,
                 EndSymbolizationHook end_hook);
 
+  void RefreshModules(bool fallback_init);
+  const LoadedModule *SearchForModule(uptr address);
   const LoadedModule *FindModuleForAddress(uptr address);
 
   void InvalidateModuleList();
Index: lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc
===================================================================
--- lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc
+++ lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc
@@ -151,29 +151,44 @@
   return true;
 }
 
-const LoadedModule *Symbolizer::FindModuleForAddress(uptr address) {
-  bool modules_were_reloaded = false;
-  if (!modules_fresh_) {
-    modules_.init();
+void Symbolizer::RefreshModules(bool fallback_init) {
+    fallback_init ? modules_.fallbackInit() : modules_.init();
     RAW_CHECK(modules_.size() > 0);
     modules_fresh_ = true;
-    modules_were_reloaded = true;
-  }
+}
+
+const LoadedModule *Symbolizer::SearchForModule(uptr address) {
   for (uptr i = 0; i < modules_.size(); i++) {
     if (modules_[i].containsAddress(address)) {
       return &modules_[i];
     }
   }
+  return nullptr;
+}
+
+const LoadedModule *Symbolizer::FindModuleForAddress(uptr address) {
+  bool modules_were_reloaded = false;
+  if (!modules_fresh_) {
+    RefreshModules(false);
+    modules_were_reloaded = true;
+  }
+  const LoadedModule *module = SearchForModule(address);
+
   // dlopen/dlclose interceptors invalidate the module list, but when
   // interception is disabled, we need to retry if the lookup fails in
   // case the module list changed.
 #if !SANITIZER_INTERCEPT_DLOPEN_DLCLOSE
-  if (!modules_were_reloaded) {
-    modules_fresh_ = false;
-    return FindModuleForAddress(address);
+  if (!module && !modules_were_reloaded) {
+    RefreshModules(false);
+    module = SearchForModule(address);
   }
 #endif
-  return 0;
+
+  if (!module) {
+    RefreshModules(true);
+    module = SearchForModule(address);
+  }
+  return module;
 }
 
 Symbolizer *Symbolizer::GetOrInit() {
Index: lib/sanitizer_common/sanitizer_win.cc
===================================================================
--- lib/sanitizer_common/sanitizer_win.cc
+++ lib/sanitizer_common/sanitizer_win.cc
@@ -583,7 +583,11 @@
     modules_.push_back(cur_module);
   }
   UnmapOrDie(hmodules, modules_buffer_size);
-};
+}
+
+void ListOfModules::fallbackInit() {
+  init();
+}
 
 // We can't use atexit() directly at __asan_init time as the CRT is not fully
 // initialized at this point.  Place the functions into a vector and use