diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -677,6 +677,10 @@
       preprocessorOptions.searchDirectoriesFromDashI.begin(),
       preprocessorOptions.searchDirectoriesFromDashI.end());
 
+  // Add the location of omp_lib.h to the search directories. Currently this is
+  // identical to the modules' directory.
+  fortranOptions.searchDirectories.emplace_back(getIntrinsicDir());
+
   // Add the ordered list of -intrinsic-modules-path
   fortranOptions.searchDirectories.insert(
       fortranOptions.searchDirectories.end(),
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
@@ -57,3 +57,5 @@
   add_custom_target(flang ALL DEPENDS ${CMAKE_BINARY_DIR}/bin/flang)
   install(PROGRAMS ${CMAKE_BINARY_DIR}/bin/flang DESTINATION "${CMAKE_INSTALL_BINDIR}")
 endif()
+
+file(COPY ${FLANG_SOURCE_DIR}/module/omp_lib.h DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/flang" FILE_PERMISSIONS OWNER_READ OWNER_WRITE)