Index: cfe/trunk/include/clang/Basic/CodeGenOptions.def
===================================================================
--- cfe/trunk/include/clang/Basic/CodeGenOptions.def
+++ cfe/trunk/include/clang/Basic/CodeGenOptions.def
@@ -61,6 +61,7 @@
 CODEGENOPT(DebugPassManager, 1, 0) ///< Prints debug information for the new
                                    ///< pass manager.
 CODEGENOPT(DisableRedZone    , 1, 0) ///< Set when -mno-red-zone is enabled.
+CODEGENOPT(EnableDebugEntryValues, 1, 0) ///< Emit call site parameter dbg info
 CODEGENOPT(IndirectTlsSegRefs, 1, 0) ///< Set when -mno-tls-direct-seg-refs
                                      ///< is specified.
 CODEGENOPT(DisableTailCalls  , 1, 0) ///< Do not emit tail calls.
Index: cfe/trunk/include/clang/Driver/CC1Options.td
===================================================================
--- cfe/trunk/include/clang/Driver/CC1Options.td
+++ cfe/trunk/include/clang/Driver/CC1Options.td
@@ -386,6 +386,8 @@
 def fno_lto_unit: Flag<["-"], "fno-lto-unit">;
 def fthin_link_bitcode_EQ : Joined<["-"], "fthin-link-bitcode=">,
     HelpText<"Write minimized bitcode to <file> for the ThinLTO thin link only">;
+def femit_debug_entry_values : Flag<["-"], "femit-debug-entry-values">,
+    HelpText<"Enables debug info about call site parameter's entry values">;
 def fdebug_pass_manager : Flag<["-"], "fdebug-pass-manager">,
     HelpText<"Prints debug information for the new pass manager">;
 def fno_debug_pass_manager : Flag<["-"], "fno-debug-pass-manager">,
Index: cfe/trunk/lib/CodeGen/BackendUtil.cpp
===================================================================
--- cfe/trunk/lib/CodeGen/BackendUtil.cpp
+++ cfe/trunk/lib/CodeGen/BackendUtil.cpp
@@ -471,6 +471,7 @@
   Options.DebuggerTuning = CodeGenOpts.getDebuggerTuning();
   Options.EmitStackSizeSection = CodeGenOpts.StackSizeSection;
   Options.EmitAddrsig = CodeGenOpts.Addrsig;
+  Options.EnableDebugEntryValues = CodeGenOpts.EnableDebugEntryValues;
 
   if (CodeGenOpts.getSplitDwarfMode() != CodeGenOptions::NoFission)
     Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
Index: cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
===================================================================
--- cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
+++ cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
@@ -4659,7 +4659,10 @@
   // were part of DWARF v4.
   bool SupportsDWARFv4Ext =
       CGM.getCodeGenOpts().DwarfVersion == 4 &&
-      CGM.getCodeGenOpts().getDebuggerTuning() == llvm::DebuggerKind::LLDB;
+      (CGM.getCodeGenOpts().getDebuggerTuning() == llvm::DebuggerKind::LLDB ||
+       (CGM.getCodeGenOpts().EnableDebugEntryValues &&
+       CGM.getCodeGenOpts().getDebuggerTuning() == llvm::DebuggerKind::GDB));
+
   if (!SupportsDWARFv4Ext && CGM.getCodeGenOpts().DwarfVersion < 5)
     return llvm::DINode::FlagZero;
 
Index: cfe/trunk/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- cfe/trunk/lib/Frontend/CompilerInvocation.cpp
+++ cfe/trunk/lib/Frontend/CompilerInvocation.cpp
@@ -760,6 +760,13 @@
 
   Opts.DisableLLVMPasses = Args.hasArg(OPT_disable_llvm_passes);
   Opts.DisableLifetimeMarkers = Args.hasArg(OPT_disable_lifetimemarkers);
+
+  llvm::Triple T(TargetOpts.Triple);
+  llvm::Triple::ArchType Arch = T.getArch();
+  if (Opts.OptimizationLevel > 0 &&
+      (Arch == llvm::Triple::x86 || Arch == llvm::Triple::x86_64))
+    Opts.EnableDebugEntryValues = Args.hasArg(OPT_femit_debug_entry_values);
+
   Opts.DisableO0ImplyOptNone = Args.hasArg(OPT_disable_O0_optnone);
   Opts.DisableRedZone = Args.hasArg(OPT_disable_red_zone);
   Opts.IndirectTlsSegRefs = Args.hasArg(OPT_mno_tls_direct_seg_refs);
Index: cfe/trunk/test/CodeGenCXX/dbg-info-all-calls-described.cpp
===================================================================
--- cfe/trunk/test/CodeGenCXX/dbg-info-all-calls-described.cpp
+++ cfe/trunk/test/CodeGenCXX/dbg-info-all-calls-described.cpp
@@ -15,6 +15,19 @@
 // RUN: | FileCheck %s -check-prefix=HAS-ATTR \
 // RUN:     -implicit-check-not=DISubprogram -implicit-check-not=DIFlagAllCallsDescribed
 
+// Supported: DWARF4 + GDB tuning by using '-femit-debug-entry-values'
+// RUN: %clang_cc1 -femit-debug-entry-values -emit-llvm %s -o - \
+// RUN:   -O1 -disable-llvm-passes -debugger-tuning=gdb \
+// RUN:   -debug-info-kind=standalone -dwarf-version=4 \
+// RUN: | FileCheck %s -check-prefix=HAS-ATTR \
+// RUN:     -implicit-check-not=DIFlagAllCallsDescribed
+
+// Unsupported: -O0 + '-femit-debug-entry-values'
+// RUN: %clang_cc1 -femit-debug-entry-values -emit-llvm %s -o - \
+// RUN:   -O0 -disable-llvm-passes -debugger-tuning=gdb \
+// RUN:   -debug-info-kind=standalone -dwarf-version=4 \
+// RUN: | FileCheck %s -check-prefix=NO-ATTR
+
 // Supported: DWARF4 + LLDB tuning, -O1, line-tables only DI
 // RUN: %clang_cc1 -emit-llvm -triple %itanium_abi_triple %s -o - \
 // RUN:   -O1 -disable-llvm-passes \