diff --git a/lld/COFF/InputFiles.cpp b/lld/COFF/InputFiles.cpp
--- a/lld/COFF/InputFiles.cpp
+++ b/lld/COFF/InputFiles.cpp
@@ -791,11 +791,15 @@
   // causes a collision which result in only one of the objects being taken
   // into consideration at LTO time (which very likely causes undefined
   // symbols later in the link stage). So we append file offset to make
-  // filename unique.
-  MemoryBufferRef mbref(
-      mb.getBuffer(),
-      saver.save(archiveName + path +
-                 (archiveName.empty() ? "" : utostr(offsetInArchive))));
+  // filename unique. We also append the name of the output binary in case
+  // the object is compiled into multiple binaries.
+  StringRef binaryName = sys::path::filename(config->outputFile);
+  StringRef name =
+      archiveName.empty()
+          ? saver.save(path)
+          : saver.save(archiveName + path + utostr(offsetInArchive) +
+                       (config->thinLTOIndexOnly ? "." + binaryName : ""));
+  MemoryBufferRef mbref(mb.getBuffer(), name);
 
   obj = check(lto::InputFile::create(mbref));
 }
diff --git a/lld/test/COFF/thinlto-archives.ll b/lld/test/COFF/thinlto-archives.ll
--- a/lld/test/COFF/thinlto-archives.ll
+++ b/lld/test/COFF/thinlto-archives.ll
@@ -9,7 +9,14 @@
 ; RUN: lld-link -out:%T/thinlto-archives/main.exe -entry:main \
 ; RUN:     -lldsavetemps -subsystem:console %T/thinlto-archives/main.obj \
 ; RUN:     %T/thinlto-archives/a.lib %T/thinlto-archives/b.lib
-; RUN: FileCheck %s < %T/thinlto-archives/main.exe.resolution.txt
+; RUN: FileCheck %s < %T/thinlto-archives/main.exe.resolution.txt \
+; RUN:     --check-prefix=CHECK
+; RUN: lld-link -out:%T/thinlto-archives/main2.exe -entry:main \
+; RUN:     -lldsavetemps -subsystem:console %T/thinlto-archives/main.obj \
+; RUN:     %T/thinlto-archives/a.lib %T/thinlto-archives/b.lib \
+; RUN:     -thinlto-index-only
+; RUN: FileCheck %s < %T/thinlto-archives/main2.exe.resolution.txt \
+; RUN:     --check-prefix=THINLTO
 
 ; CHECK: {{/thinlto-archives/main.obj$}}
 ; CHECK: {{^-r=.*/thinlto-archives/main.obj,main,px$}}
@@ -18,6 +25,13 @@
 ; CHECK-NEXT: {{/thinlto-archives/b.libbar.obj[0-9]+$}}
 ; CHECK-NEXT: {{^-r=.*/thinlto-archives/b.libbar.obj[0-9]+,bar,p$}}
 
+; THINLTO: {{/thinlto-archives/main.obj$}}
+; THINLTO: {{^-r=.*/thinlto-archives/main.obj,main,px$}}
+; THINLTO: {{/thinlto-archives/a.libbar.obj[0-9]+.main2.exe$}}
+; THINLTO-NEXT: {{^-r=.*/thinlto-archives/a.libbar.obj[0-9]+.main2.exe,foo,p$}}
+; THINLTO-NEXT: {{/thinlto-archives/b.libbar.obj[0-9]+.main2.exe$}}
+; THINLTO-NEXT: {{^-r=.*/thinlto-archives/b.libbar.obj[0-9]+.main2.exe,bar,p$}}
+
 target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-pc-windows-msvc"