diff --git a/flang/lib/Lower/Bridge.cpp b/flang/lib/Lower/Bridge.cpp
--- a/flang/lib/Lower/Bridge.cpp
+++ b/flang/lib/Lower/Bridge.cpp
@@ -1445,7 +1445,7 @@
   }
 
   void genFIR(const Fortran::parser::CompilerDirective &) {
-    TODO(toLocation(), "CompilerDirective lowering");
+    mlir::emitWarning(toLocation(), "ignoring all compiler directives");
   }
 
   void genFIR(const Fortran::parser::OpenACCConstruct &acc) {
diff --git a/flang/test/Lower/compiler-directive.f90 b/flang/test/Lower/compiler-directive.f90
new file mode 100644
--- /dev/null
+++ b/flang/test/Lower/compiler-directive.f90
@@ -0,0 +1,13 @@
+! RUN: bbc %s -o - 2>&1 | FileCheck %s
+! RUN: %flang_fc1 -emit-fir %s -o - 2>&1 | FileCheck %s
+
+! CHECK: ignoring all compiler directives
+
+MODULE test_mod
+  CONTAINS
+  SUBROUTINE foo()
+    REAL :: var
+  !DIR$ VECTOR ALIGNED
+    var = 1.
+  END SUBROUTINE foo
+END MODULE test_mod