Index: flang/lib/Frontend/CMakeLists.txt
===================================================================
--- flang/lib/Frontend/CMakeLists.txt
+++ flang/lib/Frontend/CMakeLists.txt
@@ -42,6 +42,7 @@
   LINK_COMPONENTS
   Passes
   Analysis
+  Extensions
   IRReader
   Option
   Support
Index: flang/lib/Frontend/FrontendActions.cpp
===================================================================
--- flang/lib/Frontend/FrontendActions.cpp
+++ flang/lib/Frontend/FrontendActions.cpp
@@ -48,6 +48,7 @@
 #include "llvm/IRReader/IRReader.h"
 #include "llvm/MC/TargetRegistry.h"
 #include "llvm/Passes/PassBuilder.h"
+#include "llvm/Passes/PassPlugin.h"
 #include "llvm/Passes/StandardInstrumentations.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/SourceMgr.h"
@@ -56,6 +57,11 @@
 
 using namespace Fortran::frontend;
 
+// Declare plugin extension function declarations.
+#define HANDLE_EXTENSION(Ext)                                                  \
+  llvm::PassPluginLibraryInfo get##Ext##PluginInfo();
+#include "llvm/Support/Extension.def"
+
 //===----------------------------------------------------------------------===//
 // Custom BeginSourceFileAction
 //===----------------------------------------------------------------------===//
@@ -691,6 +697,11 @@
   si.registerCallbacks(pic, &fam);
   llvm::PassBuilder pb(tm.get(), pto, pgoOpt, &pic);
 
+  // Register static plugin extensions.
+#define HANDLE_EXTENSION(Ext)                                                  \
+  get##Ext##PluginInfo().RegisterPassBuilderCallbacks(pb);
+#include "llvm/Support/Extension.def"
+
   // Register all the basic analyses with the managers.
   pb.registerModuleAnalyses(mam);
   pb.registerCGSCCAnalyses(cgam);
Index: flang/test/CMakeLists.txt
===================================================================
--- flang/test/CMakeLists.txt
+++ flang/test/CMakeLists.txt
@@ -5,6 +5,7 @@
 llvm_canonicalize_cmake_booleans(
   FLANG_BUILD_EXAMPLES
   FLANG_STANDALONE_BUILD
+  LLVM_BYE_LINK_INTO_TOOLS
   LLVM_ENABLE_PLUGINS
 )
 
@@ -64,6 +65,10 @@
   FortranDecimal
 )
 
+if (LLVM_ENABLE_PLUGINS AND NOT WIN32)
+  list(APPEND FLANG_TEST_DEPENDS Bye)
+endif()
+
 if (FLANG_INCLUDE_TESTS)
   if (FLANG_GTEST_AVAIL)
     list(APPEND FLANG_TEST_DEPENDS FlangUnitTests)
Index: flang/test/Driver/pass-plugin.f90
===================================================================
--- /dev/null
+++ flang/test/Driver/pass-plugin.f90
@@ -0,0 +1,17 @@
+! Verify that the static and dynamically loaded pass plugins work as expected.
+
+! UNSUPPORTED: system-windows
+! TODO: Remove staticbye dependency once -fpass-plugin= option is supported.
+! REQUIRES: plugins, shell, staticbye
+
+! RUN: %flang -S %s %loadbye -Xflang -fdebug-pass-manager -o /dev/null \
+! RUN: 2>&1 | FileCheck %s
+
+! RUN: %flang_fc1 -S %s %loadbye -fdebug-pass-manager -o /dev/null \
+! RUN: 2>&1 | FileCheck %s
+
+
+! CHECK: Running pass: {{.*}}Bye on empty_
+
+subroutine empty
+end subroutine empty
Index: flang/test/lit.cfg.py
===================================================================
--- flang/test/lit.cfg.py
+++ flang/test/lit.cfg.py
@@ -58,6 +58,14 @@
 if config.has_plugins:
     config.available_features.add('plugins')
 
+if config.linked_bye_extension:
+    config.available_features.add('staticbye')
+    config.substitutions.append(('%loadbye', ''))
+else:
+    config.substitutions.append(('%loadbye',
+                                 '-fpass-plugin={}/Bye{}'.format(config.llvm_shlib_dir,
+                                                                 config.llvm_plugin_ext)))
+
 # test_source_root: The root path where tests are located.
 config.test_source_root = os.path.dirname(__file__)
 
Index: flang/test/lit.site.cfg.py.in
===================================================================
--- flang/test/lit.site.cfg.py.in
+++ flang/test/lit.site.cfg.py.in
@@ -17,6 +17,7 @@
 config.python_executable = "@PYTHON_EXECUTABLE@"
 config.flang_standalone_build = @FLANG_STANDALONE_BUILD@
 config.has_plugins = @LLVM_ENABLE_PLUGINS@
+config.linked_bye_extension = @LLVM_BYE_LINK_INTO_TOOLS@
 config.cc = "@CMAKE_C_COMPILER@"
 config.targets_to_build = "@TARGETS_TO_BUILD@"