diff --git a/compiler-rt/CMakeLists.txt b/compiler-rt/CMakeLists.txt
--- a/compiler-rt/CMakeLists.txt
+++ b/compiler-rt/CMakeLists.txt
@@ -437,10 +437,18 @@
 endif()
 
 append_list_if(COMPILER_RT_HAS_LIBC c SANITIZER_COMMON_LINK_LIBS)
+if("${CMAKE_SYSTEM_NAME}" STREQUAL "Fuchsia")
+  list(APPEND SANITIZER_COMMON_LINK_LIBS zircon)
+endif()
 
 if("${CMAKE_SYSTEM_NAME}" STREQUAL "Fuchsia")
+  set(SANITIZER_NO_UNDEFINED_SYMBOLS_DEFAULT ON)
+else()
+  set(SANITIZER_NO_UNDEFINED_SYMBOLS_DEFAULT OFF)
+endif
+option(SANITIZER_NO_UNDEFINED_SYMBOLS ${SANITIZER_NO_UNDEFINED_SYMBOLS_DEFAULT})
+if (SANITIZER_NO_UNDEFINED_SYMBOLS)
   list(APPEND SANITIZER_COMMON_LINK_FLAGS -Wl,-z,defs)
-  list(APPEND SANITIZER_COMMON_LINK_LIBS zircon)
 endif()
 
 # TODO: COMPILER_RT_COMMON_CFLAGS and COMPILER_RT_COMMON_LINK_FLAGS are