Index: flang/include/flang/Tools/CLOptions.inc
===================================================================
--- flang/include/flang/Tools/CLOptions.inc
+++ flang/include/flang/Tools/CLOptions.inc
@@ -66,6 +66,8 @@
     "rewrite boxed procedures");
 #endif
 
+DisableOption(ExternalNameConversion, "external-name-interop", "convert names with external convention");
+
 /// Generic for adding a pass to the pass manager if it is not disabled.
 template <typename F>
 void addPassConditionally(
@@ -139,6 +141,11 @@
 }
 #endif
 
+inline void addExternalNameConversionPass(mlir::PassManager &pm) {
+  addPassConditionally(pm, disableExternalNameConversion,
+      [&]() { return fir::createExternalNameConversionPass(); });
+}
+
 /// Create a pass pipeline for running default optimization passes for
 /// incremental conversion of FIR.
 ///
@@ -174,6 +181,7 @@
   pm.addNestedPass<mlir::FuncOp>(fir::createAbstractResultOptPass());
   fir::addCodeGenRewritePass(pm);
   fir::addTargetRewritePass(pm);
+  fir::addExternalNameConversionPass(pm);
   fir::addFIRToLLVMPass(pm);
 }
 
Index: flang/test/Lower/common-block.f90
===================================================================
--- flang/test/Lower/common-block.f90
+++ flang/test/Lower/common-block.f90
@@ -1,4 +1,4 @@
-! RUN: bbc %s -o - | tco | FileCheck %s
+! RUN: bbc %s -o - | tco -disable-external-name-interop | FileCheck %s
 
 ! CHECK: @_QB = common global [8 x i8] zeroinitializer
 ! CHECK: @_QBx = global { float, float } { float 1.0{{.*}}, float 2.0{{.*}} }