diff --git a/Source/cmOrderDirectories.cxx b/Source/cmOrderDirectories.cxx
index 35ee127..e3406a8 100644
--- a/Source/cmOrderDirectories.cxx
+++ b/Source/cmOrderDirectories.cxx
@@ -73,10 +73,8 @@
       {
       // Check if this directory conflicts with the entry.
       std::string const& dir = this->OD->OriginalDirectories[i];
-      if(dir != this->Directory &&
-         cmSystemTools::GetRealPath(dir) !=
-         cmSystemTools::GetRealPath(this->Directory) &&
-         this->FindConflict(dir))
+      if (!this->OD->IsSameDirectory(dir, this->Directory) &&
+          this->FindConflict(dir))
         {
         // The library will be found in this directory but this is not
         // the directory named for it.  Add an entry to make sure the
@@ -639,3 +637,23 @@
     ->IssueMessage(cmake::WARNING, e.str(),
                    this->Target->Target->GetBacktrace());
 }
+
+bool cmOrderDirectories::IsSameDirectory(std::string const& l,
+                                         std::string const& r)
+{
+  return this->GetRealPath(l) == this->GetRealPath(r);
+}
+
+std::string const& cmOrderDirectories::GetRealPath(std::string const& dir)
+{
+  std::map<std::string, std::string>::iterator i =
+    this->RealPaths.lower_bound(dir);
+  if (i == this->RealPaths.end() ||
+      this->RealPaths.key_comp()(dir, i->first))
+    {
+    typedef std::map<std::string, std::string>::value_type value_type;
+    i = this->RealPaths.insert(
+      i, value_type(dir, cmSystemTools::GetRealPath(dir)));
+    }
+  return i->second;
+}
diff --git a/Source/cmOrderDirectories.h b/Source/cmOrderDirectories.h
index 211c786..477216b 100644
--- a/Source/cmOrderDirectories.h
+++ b/Source/cmOrderDirectories.h
@@ -80,6 +80,12 @@
   struct ConflictList: public std::vector<ConflictPair> {};
   std::vector<ConflictList> ConflictGraph;
 
+  // Compare directories after resolving symlinks.
+  bool IsSameDirectory(std::string const& l, std::string const& r);
+
+  std::string const& GetRealPath(std::string const& dir);
+  std::map<std::string, std::string> RealPaths;
+
   friend class cmOrderDirectoriesConstraint;
   friend class cmOrderDirectoriesConstraintLibrary;
 };