diff --git a/clang/cmake/caches/Fuchsia-stage2.cmake b/clang/cmake/caches/Fuchsia-stage2.cmake
--- a/clang/cmake/caches/Fuchsia-stage2.cmake
+++ b/clang/cmake/caches/Fuchsia-stage2.cmake
@@ -40,7 +40,10 @@
 set(ENABLE_LINKER_BUILD_ID ON CACHE BOOL "")
 set(ENABLE_X86_RELAX_RELOCATIONS ON CACHE BOOL "")
 
-set(CMAKE_BUILD_TYPE Release CACHE STRING "")
+if (NOT DEFINED CMAKE_BUILD_TYPE)
+  set(CMAKE_BUILD_TYPE Release CACHE STRING "")
+endif()
+
 if (APPLE)
   set(CMAKE_OSX_DEPLOYMENT_TARGET "10.13" CACHE STRING "")
 elseif(WIN32)