diff --git a/flang/CMakeLists.txt b/flang/CMakeLists.txt
--- a/flang/CMakeLists.txt
+++ b/flang/CMakeLists.txt
@@ -38,6 +38,16 @@
 # Must go below project(..)
 include(GNUInstallDirs)
 
+# MSVC + clang-cl build requires clang_rt.builtin.${target} library
+if (MSVC AND CMAKE_CXX_COMPILER_ID MATCHES Clang)
+  include(HandleCompilerRT)
+  find_compiler_rt_library(builtins CLANG_RT_BUILTINS_LIBRARY)
+  get_filename_component(LIBDIR "${CLANG_RT_BUILTINS_LIBRARY}" DIRECTORY)
+  if (IS_DIRECTORY "${LIBDIR}")
+    link_libraries(${CLANG_RT_BUILTINS_LIBRARY})
+  endif()
+endif()
+
 if (FLANG_STANDALONE_BUILD)
   set(FLANG_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
   if (NOT MSVC_IDE)