3 files changed, 22 insertions, 0 deletions
diff --git a/lib/Driver/ToolChains.cpp b/lib/Driver/ToolChains.cpp
index 420573dea2..0c2db8a87c 100644
--- a/lib/Driver/ToolChains.cpp
+++ b/lib/Driver/ToolChains.cpp
@@ -526,6 +526,12 @@ bool Darwin::IsUnwindTablesDefault() const {
   return getArchName() == "x86_64";
 }
 
+bool Darwin::UseDwarfDebugFlags() const {
+  if (const char *S = ::getenv("RC_DEBUG_OPTIONS"))
+    return S[0] != '\0';
+  return false;
+}
+
 const char *Darwin::GetDefaultRelocationModel() const {
   return "pic";
 }
diff --git a/lib/Driver/ToolChains.h b/lib/Driver/ToolChains.h
index fcd96f1e5c..be36344f0c 100644
--- a/lib/Driver/ToolChains.h
+++ b/lib/Driver/ToolChains.h
@@ -154,6 +154,8 @@ public:
   virtual const char *GetDefaultRelocationModel() const;
   virtual const char *GetForcedPicModel() const;
 
+  virtual bool UseDwarfDebugFlags() const;
+
   /// }
 };
 
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 55008e3bbb..d3c1b310ed 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -1109,6 +1109,20 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
 
   const char *Exec =
     Args.MakeArgString(getToolChain().GetProgramPath(C, "clang"));
+
+  // Optionally embed the -cc1 level arguments into the debug info, for build
+  // analysis.
+  if (getToolChain().UseDwarfDebugFlags()) {
+    llvm::SmallString<256> Flags;
+    Flags += Exec;
+    for (unsigned i = 0, e = CmdArgs.size(); i != e; ++i) {
+      Flags += " ";
+      Flags += CmdArgs[i];
+    }
+    CmdArgs.push_back("-dwarf-debug-flags");
+    CmdArgs.push_back(Args.MakeArgString(Flags.str()));
+  }
+
   Dest.addCommand(new Command(JA, *this, Exec, CmdArgs));
 
   // Explicitly warn that these options are unsupported, even though