diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
index df1e65f3a588c..241f3ebc95395 100644
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -112,7 +112,7 @@ if(LLVM_INTEGRATED_CRT_ALLOC)
   if((LLVM_INTEGRATED_CRT_ALLOC MATCHES "rpmalloc$") OR LLVM_ENABLE_RPMALLOC)
     add_compile_definitions(ENABLE_OVERRIDE ENABLE_PRELOAD)
     set(ALLOCATOR_FILES "${LLVM_INTEGRATED_CRT_ALLOC}/rpmalloc/rpmalloc.c")
-    set(delayload_flags "${delayload_flags} ${WL}-INCLUDE:malloc")
+    list(APPEND delayload_flags "${WL}-INCLUDE:malloc")
   elseif(LLVM_INTEGRATED_CRT_ALLOC MATCHES "snmalloc$")
     set(ALLOCATOR_FILES "${LLVM_INTEGRATED_CRT_ALLOC}/src/snmalloc/override/new.cc")
     set(system_libs ${system_libs} "mincore.lib" "${WL}-INCLUDE:malloc")