diff --git a/projects/CMakeLists.txt b/projects/CMakeLists.txt
index 9afc30c8928..c98a8824773 100644
--- a/projects/CMakeLists.txt
+++ b/projects/CMakeLists.txt
@@ -31,6 +31,7 @@ if(${LLVM_BUILD_RUNTIME})
     # dependent projects can see the target names of their dependencies.
     add_llvm_external_project(libunwind)
     add_llvm_external_project(libcxxabi)
+    add_llvm_external_project(pstl)
     add_llvm_external_project(libcxx)
   endif()
   if(NOT LLVM_BUILD_EXTERNAL_COMPILER_RT)