diff --git a/include/llvm/Pass.h b/include/llvm/Pass.h
index 0fcf6b33eca..251620cf9af 100644
--- a/include/llvm/Pass.h
+++ b/include/llvm/Pass.h
@@ -11,7 +11,7 @@
 // Passes should extend one of the classes below, depending on the guarantees
 // that it can make about what will be modified as it is run.  For example, most
 // global optimizations should derive from FunctionPass, because they do not add
-// or delete functionss, they operate on the internals of the function.
+// or delete functions, they operate on the internals of the function.
 //
 //===----------------------------------------------------------------------===//
 
@@ -26,14 +26,9 @@ class Function;
 class Module;
 class AnalysisUsage;
 class AnalysisID;
-class Pass;
 template<class UnitType> class PassManagerT;
 struct AnalysisResolver;
 
-// PassManager - Top level PassManagerT instantiation intended to be used.
-// Implemented in PassManager.h
-typedef PassManagerT<Module> PassManager;
-
 //===----------------------------------------------------------------------===//
 // Pass interface - Implemented by all 'passes'.  Subclass this if you are an
 // interprocedural optimization or you do not fit into any of the more
@@ -143,6 +138,18 @@ struct FunctionPass : public Pass {
   //
   bool run(Function *F);
 
+protected:
+  // doesNotModifyCFG - This function should be called by our subclasses to
+  // implement the getAnalysisUsage virtual function, iff they do not:
+  //
+  //  1. Add or remove basic blocks from the function
+  //  2. Modify terminator instructions in any way.
+  //
+  // This function annotates the AnalysisUsage info object to say that analyses
+  // that only depend on the CFG are preserved by this pass.
+  //
+  void doesNotModifyCFG(AnalysisUsage &Info);
+
 private:
   friend class PassManagerT<Module>;
   friend class PassManagerT<Function>;
diff --git a/include/llvm/PassManager.h b/include/llvm/PassManager.h
new file mode 100644
index 00000000000..644e30b50c2
--- /dev/null
+++ b/include/llvm/PassManager.h
@@ -0,0 +1,36 @@
+//===- llvm/PassManager.h - Container for Passes -----------------*- C++ -*--=//
+//
+// This file defines the PassManager class.  This class is used to hold,
+// maintain, and optimize execution of Pass's.  The PassManager class ensures
+// that analysis results are available before a pass runs, and that Pass's are
+// destroyed when the PassManager is destroyed.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_PASSMANAGER_H
+#define LLVM_PASSMANAGER_H
+
+class Pass;
+class Module;
+template<class UnitType> class PassManagerT;
+
+class PassManager {
+  PassManagerT<Module> *PM;    // This is a straightforward Pimpl class
+public:
+  PassManager();
+  ~PassManager();
+
+  // add - Add a pass to the queue of passes to run.  This passes ownership of
+  // the Pass to the PassManager.  When the PassManager is destroyed, the pass
+  // will be destroyed as well, so there is no need to delete the pass.  This
+  // implies that all passes MUST be allocated with 'new'.
+  //
+  void add(Pass *P);
+
+  // run - Execute all of the passes scheduled for execution.  Keep track of
+  // whether any of the functions modifies the program, and if so, return true.
+  //
+  bool run(Module *M);
+};
+
+#endif
diff --git a/lib/VMCore/Pass.cpp b/lib/VMCore/Pass.cpp
index beef60fd470..ff9ac928b96 100644
--- a/lib/VMCore/Pass.cpp
+++ b/lib/VMCore/Pass.cpp
@@ -7,11 +7,14 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/PassManager.h"
+#include "PassManagerT.h"         // PassManagerT implementation
 #include "llvm/Module.h"
 #include "llvm/Function.h"
 #include "llvm/BasicBlock.h"
 #include "Support/STLExtras.h"
-#include <algorithm>
+#include "Support/CommandLine.h"
+#include <typeinfo>
+#include <iostream>
 
 // Source of unique analysis ID #'s.
 unsigned AnalysisID::NextID = 0;
@@ -21,15 +24,22 @@ void AnalysisResolver::setAnalysisResolver(Pass *P, AnalysisResolver *AR) {
   P->Resolver = AR;
 }
 
+//===----------------------------------------------------------------------===//
+// PassManager implementation - The PassManager class is a simple Pimpl class
+// that wraps the PassManagerT template.
+//
+PassManager::PassManager() : PM(new PassManagerT<Module>()) {}
+PassManager::~PassManager() { delete PM; }
+void PassManager::add(Pass *P) { PM->add(P); }
+bool PassManager::run(Module *M) { return PM->run(M); }
 
+
+//===----------------------------------------------------------------------===//
 // Pass debugging information.  Often it is useful to find out what pass is
 // running when a crash occurs in a utility.  When this library is compiled with
 // debugging on, a command line option (--debug-pass) is enabled that causes the
 // pass name to be printed before it executes.
 //
-#include "Support/CommandLine.h"
-#include <typeinfo>
-#include <iostream>
 
 // Different debug levels that can be enabled...
 enum PassDebugLevel {
@@ -132,6 +142,20 @@ void FunctionPass::addToPassManager(PassManagerT<Function> *PM,
   PM->addPass(this, AU);
 }
 
+// doesNotModifyCFG - This function should be called by our subclasses to
+// implement the getAnalysisUsage virtual function, iff they do not:
+//
+//  1. Add or remove basic blocks from the function
+//  2. Modify terminator instructions in any way.
+//
+// This function annotates the AnalysisUsage info object to say that analyses
+// that only depend on the CFG are preserved by this pass.
+//
+void FunctionPass::doesNotModifyCFG(AnalysisUsage &Info) {
+
+}
+
+
 //===----------------------------------------------------------------------===//
 // BasicBlockPass Implementation
 //