diff --git a/flang/CMakeLists.txt b/flang/CMakeLists.txt
--- a/flang/CMakeLists.txt
+++ b/flang/CMakeLists.txt
@@ -190,6 +190,7 @@
   include_directories(SYSTEM ${MLIR_INCLUDE_DIR})
   include_directories(SYSTEM ${MLIR_TABLEGEN_OUTPUT_DIR})
 endif()
+set(FLANG_INTRINSIC_MODULES_DIR ${CMAKE_BINARY_DIR}/include/flang)
 
 if(FLANG_BUILD_NEW_DRIVER)
     # TODO: Remove when libclangDriver is lifted out of Clang
diff --git a/flang/test/CMakeLists.txt b/flang/test/CMakeLists.txt
--- a/flang/test/CMakeLists.txt
+++ b/flang/test/CMakeLists.txt
@@ -5,8 +5,6 @@
   FLANG_STANDALONE_BUILD
 )
 
-set(FLANG_INTRINSIC_MODULES_DIR ${FLANG_BINARY_DIR}/include/flang)
-
 set(FLANG_TOOLS_DIR ${FLANG_BINARY_DIR}/bin)
 
 configure_lit_site_cfg(
diff --git a/flang/tools/f18/CMakeLists.txt b/flang/tools/f18/CMakeLists.txt
--- a/flang/tools/f18/CMakeLists.txt
+++ b/flang/tools/f18/CMakeLists.txt
@@ -30,7 +30,6 @@
   "__fortran_type_info"
 )
 
-set(include ${FLANG_BINARY_DIR}/include/flang)
 target_include_directories(f18
   PRIVATE
   ${CMAKE_CURRENT_BINARY_DIR}
@@ -38,27 +37,24 @@
 
 # Create module files directly from the top-level module source directory
 foreach(filename ${MODULES})
+  set(base ${FLANG_INTRINSIC_MODULES_DIR}/${filename})
   if(${filename} MATCHES "__fortran_type_info")
     set(depends "")
   elseif(${filename} MATCHES "__fortran_builtins")
-    set(depends ${include}/__fortran_type_info.mod)
+    set(depends ${FLANG_INTRINSIC_MODULES_DIR}/__fortran_type_info.mod)
   else()
-    set(depends ${include}/__fortran_builtins.mod)
+    set(depends ${FLANG_INTRINSIC_MODULES_DIR}/__fortran_builtins.mod)
   endif()
-  add_custom_command(OUTPUT ${include}/${filename}.mod
-    COMMAND f18 -fsyntax-only -I${include}
-      ${FLANG_SOURCE_DIR}/module/${filename}.f90
-    WORKING_DIRECTORY ${include}
+  add_custom_command(OUTPUT ${base}.mod
+    COMMAND f18 -fsyntax-only ${FLANG_SOURCE_DIR}/module/${filename}.f90
+    WORKING_DIRECTORY ${FLANG_INTRINSIC_MODULES_DIR}
     DEPENDS f18 ${FLANG_SOURCE_DIR}/module/${filename}.f90 ${depends}
   )
-  add_custom_command(OUTPUT ${include}/${filename}.f18.mod
-    DEPENDS ${include}/${filename}.mod
-    COMMAND ${CMAKE_COMMAND} -E
-      copy ${include}/${filename}.mod ${include}/${filename}.f18.mod)
-  list(APPEND MODULE_FILES ${include}/${filename}.mod)
-  list(APPEND MODULE_FILES ${include}/${filename}.f18.mod)
-  install(FILES ${include}/${filename}.mod DESTINATION include/flang)
-  install(FILES ${include}/${filename}.f18.mod DESTINATION include/flang)
+  add_custom_command(OUTPUT ${base}.f18.mod
+    DEPENDS ${base}.mod
+    COMMAND ${CMAKE_COMMAND} -E copy ${base}.mod ${base}.f18.mod)
+  list(APPEND MODULE_FILES ${base}.mod ${base}.f18.mod)
+  install(FILES ${base}.mod ${base}.f18.mod DESTINATION include/flang)
 endforeach()
 
 add_custom_target(module_files ALL DEPENDS ${MODULE_FILES})
diff --git a/flang/tools/f18/flang b/flang/tools/f18/flang
--- a/flang/tools/f18/flang
+++ b/flang/tools/f18/flang
@@ -8,11 +8,7 @@
 #===------------------------------------------------------------------------===#
 
 wd=$(cd $(dirname "$0")/.. && pwd)
-module_dir=$wd/include/flang
-if [[ ! -d $module_dir ]]; then
-  module_dir=$wd/tools/flang/include/flang
-fi
-opts="-module-suffix .f18.mod -intrinsic-module-directory $module_dir"
+opts="-module-suffix .f18.mod -intrinsic-module-directory $wd/include/flang"
 if ! $wd/bin/f18 $opts "$@"
 then status=$?
      echo flang: in $PWD, f18 failed with exit status $status: $wd/bin/f18 $opts "$@" >&2