Index: lld/Common/ErrorHandler.cpp
===================================================================
--- lld/Common/ErrorHandler.cpp
+++ lld/Common/ErrorHandler.cpp
@@ -14,6 +14,7 @@
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/Program.h"
 #include "llvm/Support/raw_ostream.h"
 #include <mutex>
 #include <regex>
@@ -216,6 +217,26 @@
     exitLld(1);
 }
 
+void ErrorHandler::error(const Twine &msg, ErrorTag tag,
+                         ArrayRef<StringRef> args) {
+  error(msg);
+  if (errorHandlingScript.empty())
+    return;
+  SmallVector<StringRef, 4> scriptArgs(2 + args.size());
+  scriptArgs[0] = errorHandlingScript;
+  switch (tag) {
+  case ErrorTag::LibNotFound:
+    scriptArgs[1] = "missing-lib";
+    break;
+  default:
+    llvm_unreachable("unsupported ErrorTag");
+  }
+  std::copy(args.begin(), args.end(), scriptArgs.begin() + 2);
+  int Res = llvm::sys::ExecuteAndWait(errorHandlingScript, scriptArgs);
+  if (Res < 0)
+    error("failed to call error handling script: " + errorHandlingScript);
+}
+
 void ErrorHandler::fatal(const Twine &msg) {
   error(msg);
   exitLld(1);
Index: lld/ELF/Driver.cpp
===================================================================
--- lld/ELF/Driver.cpp
+++ lld/ELF/Driver.cpp
@@ -277,8 +277,10 @@
 void LinkerDriver::addLibrary(StringRef name) {
   if (Optional<std::string> path = searchLibrary(name))
     addFile(*path, /*withLOption=*/true);
-  else
-    error("unable to find library -l" + name);
+  else {
+    error("unable to find library -l" + name, ErrorTag::LibNotFound,
+          {"missing-lib", name});
+  }
 }
 
 // This function is called on startup. We need this for LTO since
@@ -936,6 +938,10 @@
   config->enableNewDtags =
       args.hasFlag(OPT_enable_new_dtags, OPT_disable_new_dtags, true);
   config->entry = args.getLastArgValue(OPT_entry);
+
+  errorHandler().errorHandlingScript =
+      args.getLastArgValue(OPT_error_handling_script);
+
   config->executeOnly =
       args.hasFlag(OPT_execute_only, OPT_no_execute_only, false);
   config->exportDynamic =
Index: lld/ELF/Options.td
===================================================================
--- lld/ELF/Options.td
+++ lld/ELF/Options.td
@@ -179,6 +179,9 @@
 def error_unresolved_symbols: F<"error-unresolved-symbols">,
   HelpText<"Report unresolved symbols as errors">;
 
+defm error_handling_script: EEq<"error-handling-script",
+    "Specify an error handling script">;
+
 defm exclude_libs: Eq<"exclude-libs", "Exclude static libraries from automatic export">;
 
 defm execute_only: BB<"execute-only",
Index: lld/include/lld/Common/ErrorHandler.h
===================================================================
--- lld/include/lld/Common/ErrorHandler.h
+++ lld/include/lld/Common/ErrorHandler.h
@@ -89,11 +89,14 @@
 llvm::raw_ostream &outs();
 llvm::raw_ostream &errs();
 
+enum class ErrorTag { LibNotFound };
+
 class ErrorHandler {
 public:
   uint64_t errorCount = 0;
   uint64_t errorLimit = 20;
   StringRef errorLimitExceededMsg = "too many errors emitted, stopping now";
+  StringRef errorHandlingScript = "";
   StringRef logName = "lld";
   bool exitEarly = true;
   bool fatalWarnings = false;
@@ -101,6 +104,7 @@
   bool vsDiagnostics = false;
 
   void error(const Twine &msg);
+  void error(const Twine &msg, ErrorTag tag, ArrayRef<StringRef> args);
   LLVM_ATTRIBUTE_NORETURN void fatal(const Twine &msg);
   void log(const Twine &msg);
   void message(const Twine &msg);
@@ -118,6 +122,9 @@
 ErrorHandler &errorHandler();
 
 inline void error(const Twine &msg) { errorHandler().error(msg); }
+inline void error(const Twine &msg, ErrorTag tag, ArrayRef<StringRef> args) {
+  errorHandler().error(msg, tag, args);
+}
 inline LLVM_ATTRIBUTE_NORETURN void fatal(const Twine &msg) {
   errorHandler().fatal(msg);
 }