Index: lld/ELF/Driver.cpp
===================================================================
--- lld/ELF/Driver.cpp
+++ lld/ELF/Driver.cpp
@@ -608,9 +608,6 @@
 }
 
 static DiscardPolicy getDiscard(opt::InputArgList &args) {
-  if (args.hasArg(OPT_relocatable))
-    return DiscardPolicy::None;
-
   auto *arg =
       args.getLastArg(OPT_discard_all, OPT_discard_locals, OPT_discard_none);
   if (!arg)
Index: lld/ELF/Writer.cpp
===================================================================
--- lld/ELF/Writer.cpp
+++ lld/ELF/Writer.cpp
@@ -53,6 +53,7 @@
   void run();
 
 private:
+  void markUsedLocalSymbols();
   void copyLocalSymbols();
   void addSectionSymbols();
   void forEachRelSec(llvm::function_ref<void(InputSectionBase &)> fn);
@@ -560,8 +561,9 @@
 
 // The main function of the writer.
 template <class ELFT> void Writer<ELFT>::run() {
-  if (config->discard != DiscardPolicy::All)
-    copyLocalSymbols();
+  if (config->copyRelocs && config->discard != DiscardPolicy::None)
+    markUsedLocalSymbols();
+  copyLocalSymbols();
 
   if (config->copyRelocs)
     addSectionSymbols();
@@ -638,6 +640,33 @@
     error("failed to write to the output file: " + toString(std::move(e)));
 }
 
+template <class ELFT, class RelTy>
+static void markUsedLocalSymbolsImpl(ObjFile<ELFT> *file,
+                                     llvm::ArrayRef<RelTy> rels) {
+  for (const RelTy &rel : rels) {
+    Symbol &sym = file->getRelocTargetSym(rel);
+    if (sym.isLocal())
+      sym.used = true;
+  }
+}
+
+template <class ELFT> void Writer<ELFT>::markUsedLocalSymbols() {
+  for (InputFile *file : objectFiles) {
+    ObjFile<ELFT> *f = cast<ObjFile<ELFT>>(file);
+    for (Symbol *b : f->getLocalSymbols())
+      b->used = false;
+    for (InputSectionBase *s : f->getSections()) {
+      InputSection *isec = dyn_cast_or_null<InputSection>(s);
+      if (!isec)
+        continue;
+      if (isec->type == SHT_REL)
+        markUsedLocalSymbolsImpl(f, isec->getDataAs<typename ELFT::Rel>());
+      else if (isec->type == SHT_RELA)
+        markUsedLocalSymbolsImpl(f, isec->getDataAs<typename ELFT::Rela>());
+    }
+  }
+}
+
 static bool shouldKeepInSymtab(const Defined &sym) {
   if (sym.isSection())
     return false;
@@ -645,11 +674,12 @@
   if (config->discard == DiscardPolicy::None)
     return true;
 
-  // If -emit-reloc is given, all symbols including local ones need to be
-  // copied because they may be referenced by relocations.
-  if (config->emitRelocs)
+  if (config->copyRelocs && sym.used)
     return true;
 
+  if (config->discard == DiscardPolicy::All)
+    return false;
+
   // In ELF assembly .L symbols are normally discarded by the assembler.
   // If the assembler fails to do so, the linker discards them if
   // * --discard-locals is used.
Index: lld/test/ELF/discard-locals-preserve-used.s
===================================================================
--- /dev/null
+++ lld/test/ELF/discard-locals-preserve-used.s
@@ -0,0 +1,47 @@
+## This test checks that --discard-all and --discard-locals, when used with -r
+## or --emit-relocs, preserve local symbols which are used in relocations and
+## remove only unreferenced ones.
+
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64 -save-temp-labels %s -o %t
+
+# RUN: ld.lld --discard-none -shared --emit-relocs %t -o - | \
+# RUN:   llvm-nm - | FileCheck %s --check-prefix=DISCARD_NONE
+
+# RUN: ld.lld --discard-locals -shared --emit-relocs %t -o - | \
+# RUN:   llvm-nm - | FileCheck %s --check-prefix=DISCARD_LOCALS
+
+# RUN: ld.lld --discard-all -shared --emit-relocs %t -o - | \
+# RUN:   llvm-nm - | FileCheck %s --check-prefix=DISCARD_ALL
+
+# RUN: ld.lld --discard-none -r %t -o - | \
+# RUN:   llvm-nm - | FileCheck %s --check-prefix=DISCARD_NONE
+
+# RUN: ld.lld --discard-locals -r %t -o - | \
+# RUN:   llvm-nm - | FileCheck %s --check-prefix=DISCARD_LOCALS
+
+# RUN: ld.lld --discard-all -r %t -o - | \
+# RUN:   llvm-nm - | FileCheck %s --check-prefix=DISCARD_ALL
+
+# DISCARD_NONE:      .LUnused
+# DISCARD_NONE-NEXT: .LUsed
+# DISCARD_NONE-NEXT: Unused
+# DISCARD_NONE-NEXT: Used
+
+# DISCARD_LOCALS-NOT:  .LUnused
+# DISCARD_LOCALS:      .LUsed
+# DISCARD_LOCALS-NEXT: Unused
+# DISCARD_LOCALS-NEXT: Used
+
+# DISCARD_ALL-NOT:  .LUnused
+# DISCARD_ALL:      .LUsed
+# DISCARD_ALL-NOT:  Unused
+# DISCARD_ALL-NEXT: Used
+
+.text
+    jmp .LUsed@PLT
+    call Used@PLT
+.LUnused:
+Unused:
+.LUsed:
+Used: