Index: COFF/Driver.cpp
===================================================================
--- COFF/Driver.cpp
+++ COFF/Driver.cpp
@@ -188,8 +188,9 @@
       Archive *archive = file.get();
       make<std::unique_ptr<Archive>>(std::move(file)); // take ownership
 
+      std::uint64_t memberOffset = 0;
       for (MemoryBufferRef m : getArchiveMembers(archive))
-        addArchiveBuffer(m, "<whole-archive>", filename, 0);
+        addArchiveBuffer(m, "<whole-archive>", filename, memberOffset++);
       return;
     }
     symtab->addFile(make<ArchiveFile>(mbref));
Index: test/COFF/thinlto-whole-archives.ll
===================================================================
--- test/COFF/thinlto-whole-archives.ll
+++ test/COFF/thinlto-whole-archives.ll
@@ -0,0 +1,30 @@
+; REQUIRES: x86
+; RUN: rm -fr %T/thinlto-whole-archives
+; RUN: mkdir %T/thinlto-whole-archives %T/thinlto-whole-archives/a %T/thinlto-whole-archives/b
+; RUN: opt -thinlto-bc -o %T/thinlto-whole-archives/main.obj %s
+; RUN: opt -thinlto-bc -o %T/thinlto-whole-archives/a/bar.obj %S/Inputs/lto-dep.ll
+; RUN: opt -thinlto-bc -o %T/thinlto-whole-archives/b/bar.obj %S/Inputs/bar.ll
+; RUN: llvm-ar crs %T/thinlto-whole-archives/a.lib %T/thinlto-whole-archives/a/bar.obj %T/thinlto-whole-archives/b/bar.obj
+; RUN: lld-link -out:%T/thinlto-whole-archives/main.exe -entry:main \
+; RUN:     -wholearchive -lldsavetemps -subsystem:console %T/thinlto-whole-archives/main.obj \
+; RUN:     %T/thinlto-whole-archives/a.lib
+; RUN: FileCheck %s < %T/thinlto-whole-archives/main.exe.resolution.txt
+
+; CHECK: {{/thinlto-whole-archives/main.obj$}}
+; CHECK: {{^-r=.*/thinlto-whole-archives/main.obj,main,px$}}
+; CHECK: {{/thinlto-whole-archives/a.libbar.obj[0-9]+$}}
+; CHECK-NEXT: {{^-r=.*/thinlto-whole-archives/a.libbar.obj[0-9]+,foo,p$}}
+; CHECK-NEXT: {{/thinlto-whole-archives/a.libbar.obj[0-9]+$}}
+; CHECK-NEXT: {{^-r=.*/thinlto-whole-archives/a.libbar.obj[0-9]+,bar,p$}}
+
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc"
+
+declare void @bar()
+declare void @foo()
+
+define i32 @main() {
+  call void @foo()
+  call void @bar()
+  ret i32 0
+}