diff --git a/llvm/cmake/modules/LLVMExternalProjectUtils.cmake b/llvm/cmake/modules/LLVMExternalProjectUtils.cmake
--- a/llvm/cmake/modules/LLVMExternalProjectUtils.cmake
+++ b/llvm/cmake/modules/LLVMExternalProjectUtils.cmake
@@ -56,12 +56,14 @@
 #     Use provided strip tool instead of the default one.
 #   TARGET_TRIPLE triple
 #     Optional target triple to pass to the compiler
+#   BYPRODUCTS files...
+#     Files generated as a byproduct of this build.
 #   )
 function(llvm_ExternalProject_Add name source_dir)
   cmake_parse_arguments(ARG
     "USE_TOOLCHAIN;EXCLUDE_FROM_ALL;NO_INSTALL;ALWAYS_CLEAN"
     "SOURCE_DIR"
-    "CMAKE_ARGS;TOOLCHAIN_TOOLS;RUNTIME_LIBRARIES;DEPENDS;EXTRA_TARGETS;PASSTHROUGH_PREFIXES;STRIP_TOOL;TARGET_TRIPLE"
+    "CMAKE_ARGS;TOOLCHAIN_TOOLS;RUNTIME_LIBRARIES;DEPENDS;EXTRA_TARGETS;PASSTHROUGH_PREFIXES;STRIP_TOOL;TARGET_TRIPLE;BYPRODUCTS"
     ${ARGN})
   canonicalize_tool_name(${name} nameCanon)
 
@@ -322,6 +324,7 @@
     INSTALL_COMMAND ""
     STEP_TARGETS configure build
     BUILD_ALWAYS 1
+    BUILD_BYPRODUCTS ${ARG_BYPRODUCTS}
     USES_TERMINAL_CONFIGURE 1
     USES_TERMINAL_BUILD 1
     USES_TERMINAL_INSTALL 1
diff --git a/llvm/runtimes/CMakeLists.txt b/llvm/runtimes/CMakeLists.txt
--- a/llvm/runtimes/CMakeLists.txt
+++ b/llvm/runtimes/CMakeLists.txt
@@ -220,13 +220,11 @@
   endforeach()
 
   if(LLVM_INCLUDE_TESTS)
-    include(${LLVM_BINARY_DIR}/runtimes/Tests.cmake OPTIONAL RESULT_VARIABLE have_tests)
+    include(${LLVM_BINARY_DIR}/runtimes/Tests.cmake OPTIONAL)
     set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${LLVM_BINARY_DIR}/runtimes/Tests.cmake)
-    if(have_tests)
-      set_property(GLOBAL APPEND PROPERTY LLVM_LIT_TESTSUITES ${RUNTIMES_LIT_TESTSUITES})
-      set_property(GLOBAL APPEND PROPERTY LLVM_LIT_PARAMS ${RUNTIMES_LIT_PARAMS})
-      set_property(GLOBAL APPEND PROPERTY LLVM_LIT_EXTRA_ARGS ${RUNTIMES_LIT_EXTRA_ARGS})
-    endif()
+    set_property(GLOBAL APPEND PROPERTY LLVM_LIT_TESTSUITES ${SUB_LIT_TESTSUITES})
+    set_property(GLOBAL APPEND PROPERTY LLVM_LIT_PARAMS ${SUB_LIT_PARAMS})
+    set_property(GLOBAL APPEND PROPERTY LLVM_LIT_EXTRA_ARGS ${SUB_LIT_EXTRA_ARGS})
     list(APPEND test_targets runtimes-test-depends check-runtimes)
   endif()
 
@@ -262,6 +260,7 @@
                                          ${SUB_INSTALL_TARGETS}
                            USE_TOOLCHAIN
                            TARGET_TRIPLE ${LLVM_TARGET_TRIPLE}
+                           BYPRODUCTS ${LLVM_BINARY_DIR}/runtimes/Tests.cmake
                            ${EXTRA_ARGS})
 endfunction()
 
@@ -303,13 +302,11 @@
   endforeach()
 
   if(LLVM_INCLUDE_TESTS)
-    include(${LLVM_BINARY_DIR}/runtimes/${name}/Tests.cmake OPTIONAL RESULT_VARIABLE have_tests)
+    include(${LLVM_BINARY_DIR}/runtimes/${name}/Tests.cmake OPTIONAL)
     set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${LLVM_BINARY_DIR}/runtimes/${name}/Tests.cmake)
-    if(have_tests)
-      set_property(GLOBAL APPEND PROPERTY LLVM_LIT_TESTSUITES ${RUNTIMES_LIT_TESTSUITES})
-      set_property(GLOBAL APPEND PROPERTY LLVM_LIT_PARAMS ${RUNTIMES_LIT_PARAMS})
-      set_property(GLOBAL APPEND PROPERTY LLVM_LIT_EXTRA_ARGS ${RUNTIMES_LIT_EXTRA_ARGS})
-    endif()
+    set_property(GLOBAL APPEND PROPERTY LLVM_LIT_TESTSUITES ${SUB_LIT_TESTSUITES})
+    set_property(GLOBAL APPEND PROPERTY LLVM_LIT_PARAMS ${SUB_LIT_PARAMS})
+    set_property(GLOBAL APPEND PROPERTY LLVM_LIT_EXTRA_ARGS ${SUB_LIT_EXTRA_ARGS})
     set(runtimes-test-depends-${name} runtimes-test-depends)
     set(check-runtimes-${name} check-runtimes)
     list(APPEND ${name}_test_targets runtimes-test-depends-${name} check-runtimes-${name})
@@ -369,6 +366,7 @@
                                          ${${name}_test_targets}
                            USE_TOOLCHAIN
                            TARGET_TRIPLE ${target}
+                           BYPRODUCTS ${LLVM_BINARY_DIR}/runtimes/${name}/Tests.cmake
                            ${EXTRA_ARGS})
 endfunction()
 
diff --git a/runtimes/Tests.cmake.in b/runtimes/Tests.cmake.in
--- a/runtimes/Tests.cmake.in
+++ b/runtimes/Tests.cmake.in
@@ -1,3 +1,3 @@
-set(RUNTIMES_LIT_TESTSUITES @RUNTIMES_LIT_TESTSUITES@)
-set(RUNTIMES_LIT_PARAMS @RUNTIMES_LIT_PARAMS@)
-set(RUNTIMES_LIT_EXTRA_ARGS @RUNTIMES_LIT_EXTRA_ARGS@)
+set(SUB_LIT_TESTSUITES @RUNTIMES_LIT_TESTSUITES@)
+set(SUB_LIT_PARAMS @RUNTIMES_LIT_PARAMS@)
+set(SUB_LIT_EXTRA_ARGS @RUNTIMES_LIT_EXTRA_ARGS@)