Index: include/llvm-c/lto.h
===================================================================
--- include/llvm-c/lto.h
+++ include/llvm-c/lto.h
@@ -57,6 +57,7 @@
     LTO_SYMBOL_DEFINITION_WEAK             = 0x00000300,
     LTO_SYMBOL_DEFINITION_UNDEFINED        = 0x00000400,
     LTO_SYMBOL_DEFINITION_WEAKUNDEF        = 0x00000500,
+    LTO_SYMBOL_DEFINITION_COMDAT           = 0x00000600,
     LTO_SYMBOL_SCOPE_MASK                  = 0x00003800,
     LTO_SYMBOL_SCOPE_INTERNAL              = 0x00000800,
     LTO_SYMBOL_SCOPE_HIDDEN                = 0x00001000,
Index: lib/LTO/LTOModule.cpp
===================================================================
--- lib/LTO/LTOModule.cpp
+++ lib/LTO/LTOModule.cpp
@@ -448,7 +448,9 @@
   }
 
   // set definition part
-  if (def->hasWeakLinkage() || def->hasLinkOnceLinkage())
+  if (def->hasComdat())
+    attr |= LTO_SYMBOL_DEFINITION_COMDAT;
+  else if (def->hasWeakLinkage() || def->hasLinkOnceLinkage())
     attr |= LTO_SYMBOL_DEFINITION_WEAK;
   else if (def->hasCommonLinkage())
     attr |= LTO_SYMBOL_DEFINITION_TENTATIVE;