diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp
@@ -59,21 +59,16 @@
   return name;
 }
 
-// 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.
+// As of now, there are no headers for the Swift runtime. Provide a weak version
+// of that symbol and rely on weak symbol resolution to pick the right one.
 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");
-  (void)dlerror(); // Cleanup error message in case of failure
-}
+extern "C" SANITIZER_WEAK_ATTRIBUTE swift_demangle_ft swift_demangle = nullptr;
+
+static swift_demangle_ft swift_demangle_f;
+static void InitializeSwiftDemangler() { swift_demangle_f = swift_demangle; }
 
 // Attempts to demangle a Swift name. The demangler will return nullptr if a
 // non-Swift name is passed in.