diff --git a/lld/ELF/ScriptParser.cpp b/lld/ELF/ScriptParser.cpp
--- a/lld/ELF/ScriptParser.cpp
+++ b/lld/ELF/ScriptParser.cpp
@@ -328,8 +328,12 @@
 
 void ScriptParser::readExtern() {
   expect("(");
-  while (!errorCount() && !consume(")"))
-    Config->Undefined.push_back(unquote(next()));
+  while (!errorCount() && !consume(")")) {
+    StringRef Name = unquote(next());
+    Symtab->addSymbol(
+      Undefined{nullptr, Name, STB_GLOBAL, STV_DEFAULT, 0});
+    Config->Undefined.push_back(Name);
+  }
 }
 
 void ScriptParser::readGroup() {
diff --git a/lld/test/ELF/linkerscript/extern.s b/lld/test/ELF/linkerscript/extern.s
new file mode 100644
--- /dev/null
+++ b/lld/test/ELF/linkerscript/extern.s
@@ -0,0 +1,33 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+# RUN: echo "EXTERN( test )" > %t.script
+# RUN: echo "EXTERN( "test" )" >> %t.script
+# RUN: echo "EXTERN( "test2" )" >> %t.script
+# RUN: ld.lld %t -o %t2 -T %t.script
+# RUN: llvm-readobj -t %t2 | FileCheck %s
+
+.globl _start
+_start:
+  ret
+
+## Test that the script adds the specified symbols, and that they
+## are marked as undefined.
+
+# CHECK:      Symbol {
+# CHECK:        Name: test (1)
+# CHECK-NEXT:    Value: 0x0
+# CHECK-NEXT:    Size: 0
+# CHECK-NEXT:    Binding: Global (0x1)
+# CHECK-NEXT:    Type: None (0x0)
+# CHECK-NEXT:    Other: 0
+# CHECK-NEXT:    Section: Undefined (0x0)
+# CHECK-NEXT:  }
+# CHECK-NEXT:  Symbol {
+# CHECK-NEXT:    Name: test2 (6)
+# CHECK-NEXT:    Value: 0x0
+# CHECK-NEXT:    Size: 0
+# CHECK-NEXT:    Binding: Global (0x1)
+# CHECK-NEXT:    Type: None (0x0)
+# CHECK-NEXT:    Other: 0
+# CHECK-NEXT:    Section: Undefined (0x0)
+# CHECK-NEXT:  }