Index: llvm/trunk/test/tools/llvm-objcopy/ELF/localize.test
===================================================================
--- llvm/trunk/test/tools/llvm-objcopy/ELF/localize.test
+++ llvm/trunk/test/tools/llvm-objcopy/ELF/localize.test
@@ -1,6 +1,7 @@
 # RUN: yaml2obj %s > %t
 # RUN: llvm-objcopy \
 # RUN:     --localize-symbol Global \
+# RUN:     -L GlobalUndef \
 # RUN:     -L Local \
 # RUN:     -L Weak \
 # RUN:     -L GlobalCommon \
@@ -45,6 +46,8 @@
       Size:     8
       Section:  .text
       Value:    0x1010
+    - Name:     GlobalUndef
+      Type:     STT_FUNC
     - Name:     GlobalCommon
       Type:     STT_OBJECT
       Index:    SHN_COMMON
@@ -89,6 +92,15 @@
 #CHECK-NEXT:    Section: .text
 #CHECK-NEXT:  }
 #CHECK-NEXT:  Symbol {
+#CHECK-NEXT:    Name: GlobalUndef
+#CHECK-NEXT:    Value:
+#CHECK-NEXT:    Size:
+#CHECK-NEXT:    Binding: Global
+#CHECK-NEXT:    Type: Function
+#CHECK-NEXT:    Other:
+#CHECK-NEXT:    Section: Undefined
+#CHECK-NEXT:  }
+#CHECK-NEXT:  Symbol {
 #CHECK-NEXT:    Name: GlobalCommon
 #CHECK-NEXT:    Value: 0x2006
 #CHECK-NEXT:    Size: 2
Index: llvm/trunk/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
===================================================================
--- llvm/trunk/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
+++ llvm/trunk/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
@@ -287,7 +287,9 @@
   // them.
   if (Obj.SymbolTable) {
     Obj.SymbolTable->updateSymbols([&](Symbol &Sym) {
-      if (!Sym.isCommon() &&
+      // Common and undefined symbols don't make sense as local symbols, and can
+      // even cause crashes if we localize those, so skip them.
+      if (!Sym.isCommon() && Sym.getShndx() != SHN_UNDEF &&
           ((Config.LocalizeHidden &&
             (Sym.Visibility == STV_HIDDEN || Sym.Visibility == STV_INTERNAL)) ||
            is_contained(Config.SymbolsToLocalize, Sym.Name)))