diff --git a/compiler-rt/CMakeLists.txt b/compiler-rt/CMakeLists.txt
--- a/compiler-rt/CMakeLists.txt
+++ b/compiler-rt/CMakeLists.txt
@@ -548,7 +548,8 @@
     # If we have a valid source tree, generate llvm-lit into the bin directory.
     # The user can still choose to have the check targets *use* a different lit
     # by specifying -DLLVM_EXTERNAL_LIT, but we generate it regardless.
-    if (EXISTS ${LLVM_MAIN_SRC_DIR}/utils/llvm-lit)
+    # Don't build llvm-lit for runtimes-build, it will clean up map_config.
+    if (EXISTS ${LLVM_MAIN_SRC_DIR}/utils/llvm-lit AND NOT RUNTIMES_BUILD)
       # Needed for lit support in standalone builds.
       include(AddLLVM)
       add_subdirectory(${LLVM_MAIN_SRC_DIR}/utils/llvm-lit ${CMAKE_CURRENT_BINARY_DIR}/llvm-lit)