Index: lld/Common/ErrorHandler.cpp
===================================================================
--- lld/Common/ErrorHandler.cpp
+++ lld/Common/ErrorHandler.cpp
@@ -239,6 +239,9 @@
   case ErrorTag::LibNotFound:
     scriptArgs.push_back("missing-lib");
     break;
+  case ErrorTag::SymbolNotFound:
+    scriptArgs.push_back("undefined-symbol");
+    break;
   default:
     llvm_unreachable("unsupported ErrorTag");
   }
Index: lld/ELF/Relocations.cpp
===================================================================
--- lld/ELF/Relocations.cpp
+++ lld/ELF/Relocations.cpp
@@ -919,7 +919,7 @@
   if (undef.isWarning)
     warn(msg);
   else
-    error(msg);
+    error(msg, ErrorTag::SymbolNotFound, {toString(sym)});
 }
 
 template <class ELFT> void elf::reportUndefinedSymbols() {
Index: lld/docs/ld.lld.1
===================================================================
--- lld/docs/ld.lld.1
+++ lld/docs/ld.lld.1
@@ -184,15 +184,15 @@
 .It Fl -error-handing-script Ns = Ns Ar script_path
 Call script
 .Ar script_path
-when failing to find a library, with
+upon some error, with
 .Ar tag
-as first argument, and the name of the missing library as second argument.
-The script is expected to return 0 on success, 1 if
-.Ar tag
-is not supported. Any other value is considered a generic error.
+as first argument, and an extra parameter as second argument. The script is expected to return 0 on success, any other value is considered a generic error.
 .Ar tag
 may be
-.Cm missing-lib.
+.Cm missing-lib
+followed by the name of the missing library, or
+.Cm undefined-symbol
+followed by the name of the undefined symbol.
 .It Fl -execute-only
 Mark executable sections unreadable.
 This option is currently only supported on AArch64.
Index: lld/include/lld/Common/ErrorHandler.h
===================================================================
--- lld/include/lld/Common/ErrorHandler.h
+++ lld/include/lld/Common/ErrorHandler.h
@@ -89,7 +89,7 @@
 llvm::raw_ostream &outs();
 llvm::raw_ostream &errs();
 
-enum class ErrorTag { LibNotFound };
+enum class ErrorTag { LibNotFound, SymbolNotFound };
 
 class ErrorHandler {
 public:
Index: lld/test/ELF/error-handling-script-linux.test
===================================================================
--- lld/test/ELF/error-handling-script-linux.test
+++ lld/test/ELF/error-handling-script-linux.test
@@ -6,10 +6,21 @@
 # RUN: not ld.lld -o /dev/null -lidontexist --error-handling-script=%s %t0.o 2>&1 | FileCheck --check-prefix=CHECK-LIB %s
 # RUN: not ld.lld -o /dev/null -lidontexist --error-handling-script=%s.nope %t0.o 2>&1 | FileCheck --check-prefix=CHECK-SCRIPT-DOES-NOT-EXIST %s
 
+# RUN: echo 'bar: movl a(%rip), %eax' | llvm-mc -filetype=obj -triple=x86_64-unknown-linux - -o %t1.o
+# RUN: not ld.lld -o /dev/null --error-handling-script=%s %t1.o 2>&1 | FileCheck --check-prefix=CHECK-SYM-C %s
+
+# RUN: echo 'bar: movl _Z1av(%rip), %eax' | llvm-mc -filetype=obj -triple=x86_64-unknown-linux - -o %t1.o
+# RUN: not ld.lld -o /dev/null --demangle --error-handling-script=%s %t1.o 2>&1 | FileCheck --check-prefix=CHECK-SYM-CXX-DEMANGLE %s
+# RUN: not ld.lld -o /dev/null --no-demangle --error-handling-script=%s %t1.o 2>&1 | FileCheck --check-prefix=CHECK-SYM-CXX-NO-DEMANGLE %s
+
 # CHECK-LIB:      script: info: called with missing-lib idontexist
 # CHECK-LIB-NEXT: ld.lld: error: unable to find library -lidontexist
 
 # CHECK-SCRIPT-DOES-NOT-EXIST:      ld.lld: error: unable to find library -lidontexist
 # CHECK-SCRIPT-DOES-NOT-EXIST-NEXT: '{{.*}}': error handling script failed to execute
 
+# CHECK-SYM-C:                  script: info: called with undefined-symbol a
+# CHECK-SYM-CXX-DEMANGLE:       script: info: called with undefined-symbol a
+# CHECK-SYM-CXX-NO-DEMANGLE:    script: info: called with undefined-symbol _Z1av
+
 echo "script: info: called with $*"