diff --git a/lib/Debugger/SourceLanguage-Unknown.cpp b/lib/Debugger/SourceLanguage-Unknown.cpp
new file mode 100644
index 0000000..c5d912a
--- /dev/null
+++ b/lib/Debugger/SourceLanguage-Unknown.cpp
@@ -0,0 +1,138 @@
+//===-- SourceLanguage-Unknown.cpp - Implement itf for unknown languages --===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// If the LLVM debugger does not have a module for a particular language, it
+// falls back on using this one to perform the source-language interface.  This
+// interface is not wonderful, but it gets the job done.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Debugger/SourceLanguage.h"
+#include "llvm/Debugger/ProgramInfo.h"
+#include "llvm/Support/Streams.h"
+#include <cassert>
+#include <ostream>
+using namespace llvm;
+
+//===----------------------------------------------------------------------===//
+// Implement the SourceLanguage cache for the Unknown language.
+//
+
+namespace {
+  /// SLUCache - This cache allows for efficient lookup of source functions by
+  /// name.
+  ///
+  struct SLUCache : public SourceLanguageCache {
+    ProgramInfo &PI;
+    std::multimap<std::string, SourceFunctionInfo*> FunctionMap;
+  public:
+    SLUCache(ProgramInfo &pi);
+
+    typedef std::multimap<std::string, SourceFunctionInfo*>::const_iterator
+       fm_iterator;
+
+    std::pair<fm_iterator, fm_iterator>
+    getFunction(const std::string &Name) const {
+      return FunctionMap.equal_range(Name);
+    }
+
+    SourceFunctionInfo *addSourceFunction(SourceFunctionInfo *SF) {
+      FunctionMap.insert(std::make_pair(SF->getSymbolicName(), SF));
+      return SF;
+    }
+  };
+}
+
+SLUCache::SLUCache(ProgramInfo &pi) : PI(pi) {
+}
+
+
+//===----------------------------------------------------------------------===//
+// Implement SourceLanguageUnknown class, which is used to handle unrecognized
+// languages.
+//
+
+namespace {
+  struct SLU : public SourceLanguage {
+    //===------------------------------------------------------------------===//
+    // Implement the miscellaneous methods...
+    //
+    virtual const char *getSourceLanguageName() const {
+      return "unknown";
+    }
+
+    /// lookupFunction - Given a textual function name, return the
+    /// SourceFunctionInfo descriptor for that function, or null if it cannot be
+    /// found.  If the program is currently running, the RuntimeInfo object
+    /// provides information about the current evaluation context, otherwise it
+    /// will be null.
+    ///
+    virtual SourceFunctionInfo *lookupFunction(const std::string &FunctionName,
+                                               ProgramInfo &PI,
+                                               RuntimeInfo *RI = 0) const;
+
+    //===------------------------------------------------------------------===//
+    // We do use a cache for information...
+    //
+    typedef SLUCache CacheType;
+    SLUCache *createSourceLanguageCache(ProgramInfo &PI) const {
+      return new SLUCache(PI);
+    }
+
+    /// createSourceFunctionInfo - Create the new object and inform the cache of
+    /// the new function.
+    virtual SourceFunctionInfo *
+    createSourceFunctionInfo(const GlobalVariable *Desc, ProgramInfo &PI) const;
+
+  } TheUnknownSourceLanguageInstance;
+}
+
+const SourceLanguage &SourceLanguage::getUnknownLanguageInstance() {
+  return TheUnknownSourceLanguageInstance;
+}
+
+
+SourceFunctionInfo *
+SLU::createSourceFunctionInfo(const GlobalVariable *Desc,
+                              ProgramInfo &PI) const {
+  SourceFunctionInfo *Result = new SourceFunctionInfo(PI, Desc);
+  return PI.getLanguageCache(this).addSourceFunction(Result);
+}
+
+
+/// lookupFunction - Given a textual function name, return the
+/// SourceFunctionInfo descriptor for that function, or null if it cannot be
+/// found.  If the program is currently running, the RuntimeInfo object
+/// provides information about the current evaluation context, otherwise it will
+/// be null.
+///
+SourceFunctionInfo *SLU::lookupFunction(const std::string &FunctionName,
+                                        ProgramInfo &PI, RuntimeInfo *RI) const{
+  SLUCache &Cache = PI.getLanguageCache(this);
+  std::pair<SLUCache::fm_iterator, SLUCache::fm_iterator> IP
+    = Cache.getFunction(FunctionName);
+
+  if (IP.first == IP.second) {
+    if (PI.allSourceFunctionsRead())
+      return 0;  // Nothing found
+
+    // Otherwise, we might be able to find the function if we read all of them
+    // in.  Do so now.
+    PI.getSourceFunctions();
+    assert(PI.allSourceFunctionsRead() && "Didn't read in all functions?");
+    return lookupFunction(FunctionName, PI, RI);
+  }
+
+  SourceFunctionInfo *Found = IP.first->second;
+  ++IP.first;
+  if (IP.first != IP.second)
+    cout << "Whoa, found multiple functions with the same name.  I should"
+         << " ask the user which one to use: FIXME!\n";
+  return Found;
+}