Index: lldb/trunk/include/lldb/Core/ArchSpec.h
===================================================================
--- lldb/trunk/include/lldb/Core/ArchSpec.h
+++ lldb/trunk/include/lldb/Core/ArchSpec.h
@@ -277,6 +277,21 @@
     }
 
     //------------------------------------------------------------------
+    /// Merges fields from another ArchSpec into this ArchSpec.
+    ///
+    /// This will use the supplied ArchSpec to fill in any fields of
+    /// the triple in this ArchSpec which were unspecified.  This can
+    /// be used to refine a generic ArchSpec with a more specific one.
+    /// For example, if this ArchSpec's triple is something like
+    /// i386-unknown-unknown-unknown, and we have a triple which is
+    /// x64-pc-windows-msvc, then merging that triple into this one
+    /// will result in the triple i386-pc-windows-msvc.
+    ///
+    //------------------------------------------------------------------
+    void
+    MergeFrom(const ArchSpec &other);
+
+    //------------------------------------------------------------------
     /// Sets this ArchSpec according to the given architecture name.
     ///
     /// The architecture name can be one of the generic system default
Index: lldb/trunk/source/Core/ArchSpec.cpp
===================================================================
--- lldb/trunk/source/Core/ArchSpec.cpp
+++ lldb/trunk/source/Core/ArchSpec.cpp
@@ -765,6 +765,19 @@
     return IsValid();
 }
 
+void
+ArchSpec::MergeFrom(const ArchSpec &other)
+{
+    if (GetTriple().getVendor() == llvm::Triple::UnknownVendor && !TripleVendorWasSpecified())
+        GetTriple().setVendor(other.GetTriple().getVendor());
+    if (GetTriple().getOS() == llvm::Triple::UnknownOS && !TripleOSWasSpecified())
+        GetTriple().setOS(other.GetTriple().getOS());
+    if (GetTriple().getArch() == llvm::Triple::UnknownArch)
+        GetTriple().setArch(other.GetTriple().getArch());
+    if (GetTriple().getEnvironment() == llvm::Triple::UnknownEnvironment)
+        GetTriple().setEnvironment(other.GetTriple().getEnvironment());
+}
+
 bool
 ArchSpec::SetArchitecture (ArchitectureType arch_type, uint32_t cpu, uint32_t sub)
 {
Index: lldb/trunk/source/Core/Module.cpp
===================================================================
--- lldb/trunk/source/Core/Module.cpp
+++ lldb/trunk/source/Core/Module.cpp
@@ -1304,10 +1304,14 @@
                                                    data_offset);
             if (m_objfile_sp)
             {
-                // Once we get the object file, update our module with the object file's 
+                // Once we get the object file, update our module with the object file's
                 // architecture since it might differ in vendor/os if some parts were
-                // unknown.
-                m_objfile_sp->GetArchitecture (m_arch);
+                // unknown.  But since the matching arch might already be more specific
+                // than the generic COFF architecture, only merge in those values that
+                // overwrite unspecified unknown values.
+                ArchSpec new_arch;
+                m_objfile_sp->GetArchitecture(new_arch);
+                m_arch.MergeFrom(new_arch);
             }
             else
             {
Index: lldb/trunk/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp
===================================================================
--- lldb/trunk/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp
+++ lldb/trunk/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp
@@ -130,10 +130,17 @@
             {
                 ArchSpec spec;
                 if (coff_header.machine == MachineAmd64)
+                {
                     spec.SetTriple("x86_64-pc-windows");
+                    specs.Append(ModuleSpec(file, spec));
+                }
                 else if (coff_header.machine == MachineX86)
+                {
                     spec.SetTriple("i386-pc-windows");
-                specs.Append(ModuleSpec(file, spec));
+                    specs.Append(ModuleSpec(file, spec));
+                    spec.SetTriple("i686-pc-windows");
+                    specs.Append(ModuleSpec(file, spec));
+                }
             }
         }
     }