Index: ELF/SyntheticSections.cpp
===================================================================
--- ELF/SyntheticSections.cpp
+++ ELF/SyntheticSections.cpp
@@ -1545,16 +1545,33 @@
 // The ELF spec requires that all local symbols precede global symbols, so we
 // sort symbol entries in this function. (For .dynsym, we don't do that because
 // symbols for dynamic linking are inherently all globals.)
+//
+// Aside from above, we put local symbols in groups starting with the STT_FILE
+// symbol. That is convenient for purpose of identifying where are local symbols
+// coming from.
 void SymbolTableBaseSection::postThunkContents() {
   if (this->Type == SHT_DYNSYM)
     return;
-  // move all local symbols before global symbols.
-  auto It = std::stable_partition(
+
+  // Move all local symbols before global symbols.
+  auto E = std::stable_partition(
       Symbols.begin(), Symbols.end(), [](const SymbolTableEntry &S) {
         return S.Sym->isLocal() || S.Sym->computeBinding() == STB_LOCAL;
       });
-  size_t NumLocals = It - Symbols.begin();
+  size_t NumLocals = E - Symbols.begin();
   getParent()->Info = NumLocals + 1;
+
+  // Assign the growing unique ID for each local symbol's file.
+  DenseMap<InputFile *, unsigned> FileIDs;
+  for (auto I = Symbols.begin(); I != E; ++I)
+    FileIDs.insert({I->Sym->File, FileIDs.size()});
+
+  // Sort the local symbols to group them by file. We do not need to care about
+  // the STT_FILE symbols, they are already naturally placed first in each group.
+  std::stable_sort(Symbols.begin(), E,
+                   [&](const SymbolTableEntry &L, const SymbolTableEntry &R) {
+                     return FileIDs[L.Sym->File] < FileIDs[R.Sym->File];
+                   });
 }
 
 void SymbolTableBaseSection::addSymbol(Symbol *B) {
Index: ELF/Writer.cpp
===================================================================
--- ELF/Writer.cpp
+++ ELF/Writer.cpp
@@ -1663,15 +1663,15 @@
     } while (Changed);
   }
 
+  // createThunks may have added local symbols to the static symbol table
+  applySynthetic({InX::SymTab},
+                 [](SyntheticSection *SS) { SS->postThunkContents(); });
+
   // Fill other section headers. The dynamic table is finalized
   // at the end because some tags like RELSZ depend on result
   // of finalizing other sections.
   for (OutputSection *Sec : OutputSections)
     Sec->finalize<ELFT>();
-
-  // createThunks may have added local symbols to the static symbol table
-  applySynthetic({InX::SymTab},
-                 [](SyntheticSection *SS) { SS->postThunkContents(); });
 }
 
 // The linker is expected to define SECNAME_start and SECNAME_end
Index: test/ELF/local-symbols-order.s
===================================================================
--- test/ELF/local-symbols-order.s
+++ test/ELF/local-symbols-order.s
@@ -7,15 +7,16 @@
 # RUN: ld.lld -o %t %t1.o %t2.o
 # RUN: llvm-readobj -symbols -elf-output-style=GNU %t | FileCheck %s
 
-## Show the order of the local symbols produced currently by LLD.
+## Check we sort local symbols to match the
+## following order: file1, local1, hidden1, file2, local2, hidden2 ...
 
 # CHECK:      Num:    Value          Size Type    Bind   Vis      Ndx Name
 # CHECK-NEXT:   0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
 # CHECK-NEXT:   1: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS file1
 # CHECK-NEXT:   2: 0000000000201000     0 NOTYPE  LOCAL  DEFAULT    1 foo1
-# CHECK-NEXT:   3: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS file2
-# CHECK-NEXT:   4: 0000000000201000     0 NOTYPE  LOCAL  DEFAULT    1 foo2
-# CHECK-NEXT:   5: 0000000000201000     0 NOTYPE  LOCAL  HIDDEN     1 bar1
+# CHECK-NEXT:   3: 0000000000201000     0 NOTYPE  LOCAL  HIDDEN     1 bar1
+# CHECK-NEXT:   4: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS file2
+# CHECK-NEXT:   5: 0000000000201000     0 NOTYPE  LOCAL  DEFAULT    1 foo2
 # CHECK-NEXT:   6: 0000000000201000     0 NOTYPE  LOCAL  HIDDEN     1 bar2
 
 foo1:
Index: test/ELF/relocatable-comdat-multiple.s
===================================================================
--- test/ELF/relocatable-comdat-multiple.s
+++ test/ELF/relocatable-comdat-multiple.s
@@ -21,7 +21,7 @@
 # CHECK-NEXT:     Name: .group
 # CHECK-NEXT:     Index: 5
 # CHECK-NEXT:     Link: 8
-# CHECK-NEXT:     Info: 2
+# CHECK-NEXT:     Info: 6
 # CHECK-NEXT:     Type: COMDAT
 # CHECK-NEXT:     Signature: bbb
 # CHECK-NEXT:     Section(s) in group [