Index: lld/ELF/InputFiles.h
===================================================================
--- lld/ELF/InputFiles.h
+++ lld/ELF/InputFiles.h
@@ -112,6 +112,11 @@
   // True if this is an argument for --just-symbols. Usually false.
   bool JustSymbols = false;
 
+  // This is a unique monotonically-increasing number assigned to each
+  // file. This doesn't have a big role but is convenient to sort
+  // symbols quickly in a reproducible manner.
+  uint32_t FileId;
+
   // GroupId is used for --warn-backrefs which is an optional error
   // checking feature. All files within the same --{start,end}-group
   // get the same group ID. Otherwise, each file gets a new group
@@ -127,6 +132,7 @@
 private:
   const Kind FileKind;
 
+  static uint32_t NextFileId;
   static uint32_t NextGroupId;
 };
 
Index: lld/ELF/InputFiles.cpp
===================================================================
--- lld/ELF/InputFiles.cpp
+++ lld/ELF/InputFiles.cpp
@@ -39,6 +39,7 @@
 using namespace lld::elf;
 
 bool InputFile::IsInGroup;
+uint32_t InputFile::NextFileId;
 uint32_t InputFile::NextGroupId;
 std::vector<BinaryFile *> elf::BinaryFiles;
 std::vector<BitcodeFile *> elf::BitcodeFiles;
@@ -48,7 +49,7 @@
 TarWriter *elf::Tar;
 
 InputFile::InputFile(Kind K, MemoryBufferRef M)
-    : MB(M), GroupId(NextGroupId), FileKind(K) {
+    : MB(M), FileId(NextFileId++), GroupId(NextGroupId), FileKind(K) {
   // All files within the same --{start,end}-group get the same group ID.
   // Otherwise, a new file will get a new group ID.
   if (!IsInGroup)
Index: lld/ELF/SyntheticSections.cpp
===================================================================
--- lld/ELF/SyntheticSections.cpp
+++ lld/ELF/SyntheticSections.cpp
@@ -1561,18 +1561,15 @@
   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.
   // That happens because STT_FILE is always the first symbol in the object and
   // hence precede all other local symbols we add for a file.
   std::stable_sort(Symbols.begin(), E,
                    [&](const SymbolTableEntry &L, const SymbolTableEntry &R) {
-                     return FileIDs[L.Sym->File] < FileIDs[R.Sym->File];
+                     if (!L.Sym->File || !R.Sym->File)
+                       return false;
+                     return L.Sym->File->FileId < R.Sym->File->FileId;
                    });
 }
 
Index: lld/test/ELF/local-symbols-order.s
===================================================================
--- lld/test/ELF/local-symbols-order.s
+++ lld/test/ELF/local-symbols-order.s
@@ -7,26 +7,25 @@
 # RUN: ld.lld -o %t %t1.o %t2.o --emit-relocs
 # RUN: llvm-readobj -symbols -sections -elf-output-style=GNU %t | FileCheck %s
 
-## Check we sort local symbols to match the following order: 
+## Check we sort local symbols to match the following order:
 ## file1, local1, section1, hidden1, file2, local2, section2, hidden2 ...
 
 # CHECK: Section Headers:
-# CHECK:   [Nr] Name
-# CHECK:   [ [[ST:.*]]] .text
-# CHECK:   [ [[SD:.*]]] .data
-# CHECK:   [ [[SC:.*]]] .comment
+# CHECK: [ 1] .text
+# CHECK: [ 2] .data
+# CHECK: [ 3] .comment
 
 # 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: 0000000000201000     0 SECTION LOCAL  DEFAULT    [[ST]]
+# CHECK-NEXT:   3: 0000000000201000     0 SECTION LOCAL  DEFAULT    1
 # CHECK-NEXT:   4: 0000000000201000     0 NOTYPE  LOCAL  HIDDEN     1 bar1
 # CHECK-NEXT:   5: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS file2
 # CHECK-NEXT:   6: 0000000000201000     0 NOTYPE  LOCAL  DEFAULT    2 foo2
-# CHECK-NEXT:   7: 0000000000201000     0 SECTION LOCAL  DEFAULT    [[SD]]
-# CHECK-NEXT:   8: 0000000000201000     0 NOTYPE  LOCAL  HIDDEN     2 bar2
-# CHECK-NEXT:   9: 0000000000000000     0 SECTION LOCAL  DEFAULT    [[SC]]
+# CHECK-NEXT:   7: 0000000000201000     0 SECTION LOCAL  DEFAULT    2
+# CHECK-NEXT:   8: 0000000000000000     0 SECTION LOCAL  DEFAULT    3
+# CHECK-NEXT:   9: 0000000000201000     0 NOTYPE  LOCAL  HIDDEN     2 bar2
 
 foo1: