diff --git a/lldb/include/lldb/Expression/ClangASTSource.h b/lldb/include/lldb/Expression/ClangASTSource.h
index f518b8f82fbe..79819256c028 100644
--- a/lldb/include/lldb/Expression/ClangASTSource.h
+++ b/lldb/include/lldb/Expression/ClangASTSource.h
@@ -10,6 +10,8 @@
 #ifndef liblldb_ClangASTSource_h_
 #define liblldb_ClangASTSource_h_
 
+#include <set>
+
 #include "clang/Basic/IdentifierTable.h"
 #include "clang/Sema/ExternalSemaSource.h"
 
@@ -44,8 +46,9 @@ public:
     //------------------------------------------------------------------
 	ClangASTSource(clang::ASTContext &context,
                    ClangExpressionDeclMap &decl_map) : 
-        m_ast_context(context),
-        m_decl_map(decl_map) 
+        m_ast_context (context),
+        m_decl_map (decl_map),
+        m_active_lookups ()
     {
     }
     
@@ -119,6 +122,7 @@ protected:
 
 	clang::ASTContext &m_ast_context;   ///< The parser's AST context, for copying types into
 	ClangExpressionDeclMap &m_decl_map; ///< The object that looks up named entities in LLDB
+    std::set<const char *> m_active_lookups;
 };
 
 //----------------------------------------------------------------------
diff --git a/lldb/source/Expression/ClangASTSource.cpp b/lldb/source/Expression/ClangASTSource.cpp
index 7d3a8c64aa90..aa69abf1faf6 100644
--- a/lldb/source/Expression/ClangASTSource.cpp
+++ b/lldb/source/Expression/ClangASTSource.cpp
@@ -90,12 +90,21 @@ DeclContext::lookup_result ClangASTSource::FindExternalVisibleDeclsByName
         }
     }
 
-	llvm::SmallVector<NamedDecl*, 4> name_decls;
-    
-    NameSearchContext name_search_context(*this, name_decls, clang_decl_name, decl_ctx);
     ConstString const_decl_name(decl_name.c_str());
+    
+    const char *uniqued_const_decl_name = const_decl_name.GetCString();
+    if (m_active_lookups.find (uniqued_const_decl_name) != m_active_lookups.end())
+    {
+        // We are currently looking up this name...
+        return DeclContext::lookup_result();
+    }
+    m_active_lookups.insert(uniqued_const_decl_name);
+    llvm::SmallVector<NamedDecl*, 4> name_decls;    
+    NameSearchContext name_search_context(*this, name_decls, clang_decl_name, decl_ctx);
     m_decl_map.GetDecls(name_search_context, const_decl_name);
-    return SetExternalVisibleDeclsForName (decl_ctx, clang_decl_name, name_decls);
+    DeclContext::lookup_result result (SetExternalVisibleDeclsForName (decl_ctx, clang_decl_name, name_decls));
+    m_active_lookups.erase (uniqued_const_decl_name);
+    return result;
 }
 
 void ClangASTSource::MaterializeVisibleDecls(const DeclContext *DC)
diff --git a/lldb/source/Expression/ClangExpressionDeclMap.cpp b/lldb/source/Expression/ClangExpressionDeclMap.cpp
index 92b1ebb0cd0b..0ddd9efaead2 100644
--- a/lldb/source/Expression/ClangExpressionDeclMap.cpp
+++ b/lldb/source/Expression/ClangExpressionDeclMap.cpp
@@ -1024,13 +1024,13 @@ ClangExpressionDeclMap::GetDecls (NameSearchContext &context, const ConstString
             ClangNamespaceDecl namespace_decl (m_sym_ctx.FindNamespace(name));
             if (namespace_decl)
             {
-//                clang::NamespaceDecl *clang_namespace_decl = AddNamespace(context, namespace_decl);
-//                if (clang_namespace_decl)
-//                {
-//                    // TODO: is this how we get the decl lookups to be called for
-//                    // this namespace??
-//                    clang_namespace_decl->setHasExternalLexicalStorage();
-//                }
+                clang::NamespaceDecl *clang_namespace_decl = AddNamespace(context, namespace_decl);
+                if (clang_namespace_decl)
+                {
+                    // TODO: is this how we get the decl lookups to be called for
+                    // this namespace??
+                    clang_namespace_decl->setHasExternalLexicalStorage();
+                }
             }
         }
     }