Index: lib/asan/asan_rtl.cc
===================================================================
--- lib/asan/asan_rtl.cc
+++ lib/asan/asan_rtl.cc
@@ -553,6 +553,8 @@
 
   InitializeSuppressions();
 
+  Symbolizer::LateInitialize();
+
   VReport(1, "AddressSanitizer Init done\n");
 }
 
Index: lib/sanitizer_common/sanitizer_symbolizer.h
===================================================================
--- lib/sanitizer_common/sanitizer_symbolizer.h
+++ lib/sanitizer_common/sanitizer_symbolizer.h
@@ -82,6 +82,7 @@
   /// Initialize and return platform-specific implementation of symbolizer
   /// (if it wasn't already initialized).
   static Symbolizer *GetOrInit();
+  static void LateInitialize();
   // Returns a list of symbolized frames for a given address (containing
   // all inlined functions, if necessary).
   SymbolizedStack *SymbolizePC(uptr address);
Index: lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
===================================================================
--- lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
+++ lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
@@ -63,25 +63,29 @@
   return name;
 }
 
-// Attempts to demangle a Swift name. The demangler will return nullptr
-/// if a non-Swift name is passed in.
+// As of now, there are no headers for the Swift runtime. Once they are
+// present, we will weakly link since we do not require Swift runtime to be
+// linked.
+typedef char *(*swift_demangle_ft)(const char *mangledName,
+                                   size_t mangledNameLength, char *outputBuffer,
+                                   size_t *outputBufferSize, uint32_t flags);
+static swift_demangle_ft swift_demangle_f;
+
+// This must not happen lazily at symbolication time, because dlsym uses
+// malloc and thread-local storage, which is not a good thing to do during
+// symbolication.
+static void InitializeSwiftDemangler() {
+  swift_demangle_f = (swift_demangle_ft)dlsym(RTLD_DEFAULT, "swift_demangle");
+}
+
+// Attempts to demangle a Swift name. The demangler will return nullptr if a
+// non-Swift name is passed in.
 const char *DemangleSwift(const char *name) {
-  // Not to call dlsym every time we demangle, check if we are dealing with
-  // Swift mangled name first.
+  // Check if we are dealing with a Swift mangled name first.
   if (name[0] != '_' || name[1] != 'T') {
     return nullptr;
   }
 
-  // As of now, there are no headers for the Swift runtime. Once they are
-  // present, we will weakly link since we do not require Swift runtime to be
-  // linked.
-  typedef char *(*swift_demangle_ft)(const char *mangledName,
-                                     size_t mangledNameLength,
-                                     char *outputBuffer,
-                                     size_t *outputBufferSize,
-                                     uint32_t flags);
-  swift_demangle_ft swift_demangle_f =
-    (swift_demangle_ft) dlsym(RTLD_DEFAULT, "swift_demangle");
   if (swift_demangle_f)
     return swift_demangle_f(name, internal_strlen(name), 0, 0, 0);
 
@@ -485,6 +489,11 @@
   return new(symbolizer_allocator_) Symbolizer(list);
 }
 
+void Symbolizer::LateInitialize() {
+  Symbolizer::GetOrInit();
+  InitializeSwiftDemangler();
+}
+
 }  // namespace __sanitizer
 
 #endif  // SANITIZER_POSIX
Index: lib/sanitizer_common/sanitizer_symbolizer_win.cc
===================================================================
--- lib/sanitizer_common/sanitizer_symbolizer_win.cc
+++ lib/sanitizer_common/sanitizer_symbolizer_win.cc
@@ -279,6 +279,10 @@
   return new(symbolizer_allocator_) Symbolizer(list);
 }
 
+void Symbolizer::LateInitialize() {
+  Symbolizer::GetOrInit();
+}
+
 }  // namespace __sanitizer
 
 #endif  // _WIN32
Index: lib/tsan/rtl/tsan_rtl.cc
===================================================================
--- lib/tsan/rtl/tsan_rtl.cc
+++ lib/tsan/rtl/tsan_rtl.cc
@@ -369,6 +369,8 @@
 #endif
   ctx->initialized = true;
 
+  Symbolizer::LateInitialize();
+
   if (flags()->stop_on_start) {
     Printf("ThreadSanitizer is suspended at startup (pid %d)."
            " Call __tsan_resume().\n",