diff --git a/llvm/debuginfo.py b/llvm/debuginfo.py
index c9f6a2b..7afd563 100644
--- a/llvm/debuginfo.py
+++ b/llvm/debuginfo.py
@@ -13,7 +13,36 @@ bool_t  = llvm.core.Type.int(1)
 i32 = functools.partial(llvm.core.Constant.int, int32_t)
 i1  = functools.partial(llvm.core.Constant.int, bool_t)
 
-class CompileUnitDescriptor(object):
+class DebugInfoBase(object):
+    def __init__(self):
+        self.metadata_cache = {}
+
+    def get_metadata(self, llvm_module):
+        """
+        Get an existing metadata node for the given LLVM module, or build
+        one from this instance.
+        """
+        if llvm_module in self.metadata_cache:
+            node = self.metadata_cache[llvm_module]
+        else:
+            node = self.build_metadata(llvm_module)
+            self.metadata_cache[llvm_module] = node
+
+        return node
+
+    def build_metadata(self, llvm_module):
+        "Build a metadata node for the given LLVM module"
+        raise NotImplementedError
+
+    def define(self, llvm_module):
+        """
+        Define this debug descriptor as named debug metadata for the module.
+        """
+        md = self.get_metadata(llvm_module)
+        llvm.core.MetaData.add_named_operand(llvm_module, "dbg", md)
+
+
+class CompileUnitDescriptor(DebugInfoBase):
     """
     !0 = metadata !{
       i32,       ;; Tag = 17 + LLVMDebugVersion (DW_TAG_compile_unit)
@@ -37,6 +66,7 @@ class CompileUnitDescriptor(object):
                  producer, is_main=False, is_optimized=False,
                  compile_flags=None, runtime_version=0, enum_types=None,
                  retained_types=None, subprograms=None, global_vars=None):
+        super(CompileUnitDescriptor, self).__init__()
         self.langid = langid
         self.source_filename = source_filename
         self.source_filedir = source_filedir
@@ -71,14 +101,42 @@ class CompileUnitDescriptor(object):
             md(self.global_vars or []),
         ]
 
-#        for op in operands:
-#            print op
+        return md(operands)
 
-        node = llvm.core.MetaData.get(llvm_module, operands)
-        llvm.core.MetaData.add_named_operand(llvm_module, "dbg", node)
 
-#        print "printing metadata compile unit..."
-#        print node
-#        print "---- done ----"
+class FileDescriptor(DebugInfoBase):
+    """
+    !0 = metadata !{
+      i32,       ;; Tag = 41 + LLVMDebugVersion (DW_TAG_file_type)
+      metadata,  ;; Source file name
+      metadata,  ;; Source file directory (includes trailing slash)
+      metadata   ;; Unused
+    }
+    """
+
+    def __init__(self, source_filename, source_filedir, compile_unit_descriptor):
+        super(FileDescriptor, self).__init__()
+        self.source_filename = source_filename
+        self.source_filedir = source_filedir
+        self.compile_unit_descriptor = compile_unit_descriptor
+
+    @classmethod
+    def from_compileunit(cls, compile_unit_descriptor):
+        return cls(compile_unit_descriptor.source_filename,
+                   compile_unit_descriptor.source_filedir,
+                   compile_unit_descriptor)
+
+    def build_metadata(self, llvm_module):
+        md = functools.partial(llvm.core.MetaData.get, llvm_module)
+        mstr = functools.partial(llvm.core.MetaDataString.get, llvm_module)
+
+        operands = [
+            i32(_dwarf.DW_TAG_file_type + _dwarf.LLVMDebugVersion),
+            mstr(self.source_filename),
+            mstr(self.source_filedir),
+            self.compile_unit_descriptor.get_metadata(llvm_module),
+        ]
+
+        return md(operands)
+
 
-        return node
diff --git a/test/test_debuginfo.py b/test/test_debuginfo.py
index 86cbe2d..4dc0f13 100644
--- a/test/test_debuginfo.py
+++ b/test/test_debuginfo.py
@@ -42,13 +42,15 @@ class TestDebugInfo(unittest.TestCase):
             "my_cool_compiler",
         )
 
-        info.build_metadata(mod)
+        filedesc = debuginfo.FileDescriptor.from_compileunit(info)
+        filedesc.define(mod)
 
         value = square.args[0]
         result = bldr.fmul(value, value)
         bldr.ret(result)
 
 #        print mod
+
         modstr = str(mod)
         self.assertIn("my_cool_compiler", modstr)
         self.assertIn("test_debug_info.py", modstr)