Index: lld/trunk/ELF/Driver.cpp
===================================================================
--- lld/trunk/ELF/Driver.cpp
+++ lld/trunk/ELF/Driver.cpp
@@ -27,6 +27,7 @@
 using namespace llvm;
 using namespace llvm::ELF;
 using namespace llvm::object;
+using namespace llvm::sys;
 
 using namespace lld;
 using namespace lld::elf;
@@ -98,18 +99,31 @@
   return V;
 }
 
-static void dumpFile(StringRef SrcPath) {
-  SmallString<128> DirName;
-  sys::path::append(DirName, Config->Reproduce, sys::path::parent_path(SrcPath));
-  if (std::error_code EC = sys::fs::create_directories(DirName)) {
-    error(EC, "--reproduce: can't create directory");
+// Concatenates S and T so that the resulting path becomes S/T.
+// There are a few exceptions:
+//
+//  1. The result will never escape from S. Therefore, all ".."
+//     are removed from T before concatenatig them.
+//  2. Windows drive letters are removed from T before concatenation.
+static std::string concat(StringRef S, StringRef T) {
+  // Remove leading '/' or a drive letter, and then remove "..".
+  SmallString<128> T2(path::relative_path(T));
+  path::remove_dots(T2, /*remove_dot_dot=*/true);
+
+  SmallString<128> Res;
+  path::append(Res, S, T2);
+  return Res.str();
+}
+
+static void copyFile(StringRef Src, StringRef Dest) {
+  SmallString<128> Dir(Dest);
+  path::remove_filename(Dir);
+  if (std::error_code EC = sys::fs::create_directories(Dir)) {
+    error(EC, Dir + ": can't create directory");
     return;
   }
-
-  SmallString<128> DestPathName;
-  sys::path::append(DestPathName, Config->Reproduce, SrcPath);
-  if (std::error_code EC = sys::fs::copy_file(SrcPath, DestPathName))
-    error(EC, "--reproduce: can't copy file");
+  if (std::error_code EC = sys::fs::copy_file(Src, Dest))
+    error(EC, "failed to copy file: " + Dest);
 }
 
 // Opens and parses a file. Path has to be resolved already.
@@ -119,7 +133,7 @@
   if (Config->Verbose)
     llvm::outs() << Path << "\n";
   if (!Config->Reproduce.empty())
-    dumpFile(Path);
+    copyFile(Path, concat(Config->Reproduce, Path));
 
   Optional<MemoryBufferRef> Buffer = readFile(Path);
   if (!Buffer.hasValue())
@@ -241,21 +255,21 @@
   return false;
 }
 
-static void dumpLinkerInvocation(ArrayRef<const char *> Args) {
-  std::error_code EC = sys::fs::create_directories(Config->Reproduce,
-    false /* IgnoreExisting */);
-  if (EC) {
-    error(EC, "--reproduce: can't create directory");
+static void logCommandline(ArrayRef<const char *> Args) {
+  if (std::error_code EC = sys::fs::create_directories(
+        Config->Reproduce, /*IgnoreExisting=*/false)) {
+    error(EC, Config->Reproduce + ": can't create directory");
     return;
   }
 
-  SmallString<128> InvocationPath;
-  sys::path::append(InvocationPath, Config->Reproduce, "invocation.txt");
-  raw_fd_ostream OS(InvocationPath, EC, sys::fs::OpenFlags::F_None);
+  SmallString<128> Path;
+  path::append(Path, Config->Reproduce, "invocation.txt");
+  std::error_code EC;
+  raw_fd_ostream OS(Path, EC, sys::fs::OpenFlags::F_None);
   check(EC);
 
   OS << Args[0];
-  for (unsigned I = 1, E = Args.size(); I < E; ++I)
+  for (size_t I = 1, E = Args.size(); I < E; ++I)
     OS << " " << Args[I];
   OS << "\n";
 }
@@ -276,7 +290,7 @@
   readConfigs(Args);
 
   if (!Config->Reproduce.empty())
-    dumpLinkerInvocation(ArgsArr);
+    logCommandline(ArgsArr);
 
   createFiles(Args);
   checkOptions(Args);
Index: lld/trunk/test/ELF/reproduce.s
===================================================================
--- lld/trunk/test/ELF/reproduce.s
+++ lld/trunk/test/ELF/reproduce.s
@@ -1,21 +1,27 @@
 # REQUIRES: x86
 
-# RUN: rm -rf %t.dir1
-# RUN: mkdir -p %t.dir1/build
-# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.dir1/build/foo.o
-# RUN: cd %t.dir1
-# RUN: ld.lld build/foo.o -o bar -shared --as-needed --reproduce repro
-# RUN: diff build/foo.o repro/build/foo.o
+# RUN: rm -rf %t.dir
+# RUN: mkdir -p %t.dir/build1
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.dir/build1/foo.o
+# RUN: cd %t.dir
+# RUN: ld.lld build1/foo.o -o bar -shared --as-needed --reproduce repro
+# RUN: diff build1/foo.o repro/build1/foo.o
+
+# RUN: FileCheck %s --check-prefix=INVOCATION < repro/invocation.txt
+# INVOCATION: lld{{[^\s]*}} build1/foo.o -o bar -shared --as-needed --reproduce repro
+
+# RUN: mkdir -p %t.dir/build2/a/b/c
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.dir/build2/foo.o
+# RUN: cd %t.dir/build2/a/b/c
+# RUN: ld.lld ./../../../foo.o -o bar -shared --as-needed --reproduce repro
+# RUN: diff %t.dir/build2/foo.o repro/foo.o
+
+# RUN: not ld.lld build1/foo.o -o bar -shared --as-needed --reproduce . 2>&1 \
+# RUN:   | FileCheck --check-prefix=ERROR %s
+# ERROR: can't create directory
 
 .globl _start
 _start:
   mov $60, %rax
   mov $42, %rdi
   syscall
-
-# RUN: FileCheck %s --check-prefix=INVOCATION < repro/invocation.txt
-# INVOCATION: lld{{[^\s]*}} build/foo.o -o bar -shared --as-needed --reproduce repro
-
-# RUN: not ld.lld build/foo.o -o bar -shared --as-needed --reproduce repro 2>&1 \
-# RUN:   | FileCheck --check-prefix=ERROR %s
-# ERROR: --reproduce: can't create directory