Index: cfe/trunk/docs/ClangCommandLineReference.rst
===================================================================
--- cfe/trunk/docs/ClangCommandLineReference.rst
+++ cfe/trunk/docs/ClangCommandLineReference.rst
@@ -2573,6 +2573,10 @@
 
 .. option:: -gdwarf-aranges
 
+.. option:: -gembed-source
+
+.. option:: -gno-embed-source
+
 .. option:: -ggnu-pubnames
 
 .. option:: -grecord-gcc-switches, -gno-record-gcc-switches
Index: cfe/trunk/include/clang/Driver/Options.td
===================================================================
--- cfe/trunk/include/clang/Driver/Options.td
+++ cfe/trunk/include/clang/Driver/Options.td
@@ -1703,6 +1703,11 @@
     HelpText<"DWARF debug sections compression type">;
 def gz_EQ : Joined<["-"], "gz=">, Group<g_flags_Group>,
     HelpText<"DWARF debug sections compression type">;
+def gembed_source : Flag<["-"], "gembed-source">, Group<g_flags_Group>, Flags<[CC1Option]>,
+    HelpText<"Embed source text in DWARF debug sections">;
+def gno_embed_source : Flag<["-"], "gno-embed-source">, Group<g_flags_Group>,
+    Flags<[DriverOption]>,
+    HelpText<"Restore the default behavior of not embedding source text in DWARF debug sections">;
 def headerpad__max__install__names : Joined<["-"], "headerpad_max_install_names">;
 def help : Flag<["-", "--"], "help">, Flags<[CC1Option,CC1AsOption]>,
   HelpText<"Display available options">;
Index: cfe/trunk/include/clang/Frontend/CodeGenOptions.def
===================================================================
--- cfe/trunk/include/clang/Frontend/CodeGenOptions.def
+++ cfe/trunk/include/clang/Frontend/CodeGenOptions.def
@@ -318,6 +318,9 @@
 
 CODEGENOPT(NoPLT, 1, 0)
 
+/// Whether to embed source in DWARF debug line section.
+CODEGENOPT(EmbedSource, 1, 0)
+
 #undef CODEGENOPT
 #undef ENUM_CODEGENOPT
 #undef VALUE_CODEGENOPT
Index: cfe/trunk/lib/CodeGen/CGDebugInfo.h
===================================================================
--- cfe/trunk/lib/CodeGen/CGDebugInfo.h
+++ cfe/trunk/lib/CodeGen/CGDebugInfo.h
@@ -502,6 +502,9 @@
   Optional<llvm::DIFile::ChecksumKind>
   computeChecksum(FileID FID, SmallString<32> &Checksum) const;
 
+  /// Get the source of the given file ID.
+  Optional<StringRef> getSource(const SourceManager &SM, FileID FID);
+
   /// Get the file debug info descriptor for the input location.
   llvm::DIFile *getOrCreateFile(SourceLocation Loc);
 
Index: cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
===================================================================
--- cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
+++ cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
@@ -385,6 +385,19 @@
   return llvm::DIFile::CSK_MD5;
 }
 
+Optional<StringRef> CGDebugInfo::getSource(const SourceManager &SM, FileID FID) {
+  if (!CGM.getCodeGenOpts().EmbedSource)
+    return None;
+
+  bool SourceInvalid = false;
+  StringRef Source = SM.getBufferData(FID, &SourceInvalid);
+
+  if (SourceInvalid)
+    return None;
+
+  return Source;
+}
+
 llvm::DIFile *CGDebugInfo::getOrCreateFile(SourceLocation Loc) {
   if (!Loc.isValid())
     // If Location is not valid then use main input file.
@@ -416,16 +429,19 @@
 
   llvm::DIFile *F = DBuilder.createFile(remapDIPath(PLoc.getFilename()),
                                         remapDIPath(getCurrentDirname()),
-                                        CSInfo);
+                                        CSInfo,
+                                        getSource(SM, SM.getFileID(Loc)));
 
   DIFileCache[fname].reset(F);
   return F;
 }
 
 llvm::DIFile *CGDebugInfo::getOrCreateMainFile() {
-  return DBuilder.createFile(remapDIPath(TheCU->getFilename()),
-                             remapDIPath(TheCU->getDirectory()),
-                             TheCU->getFile()->getChecksum());
+  return DBuilder.createFile(
+      remapDIPath(TheCU->getFilename()),
+      remapDIPath(TheCU->getDirectory()),
+      TheCU->getFile()->getChecksum(),
+      CGM.getCodeGenOpts().EmbedSource ? TheCU->getSource() : None);
 }
 
 std::string CGDebugInfo::remapDIPath(StringRef Path) const {
@@ -558,7 +574,9 @@
   TheCU = DBuilder.createCompileUnit(
       LangTag,
       DBuilder.createFile(remapDIPath(MainFileName),
-                          remapDIPath(getCurrentDirname()), CSInfo),
+                          remapDIPath(getCurrentDirname()),
+                          CSInfo,
+                          getSource(SM, SM.getMainFileID())),
       Producer, LO.Optimize || CGOpts.PrepareForLTO || CGOpts.EmitSummaryIndex,
       CGOpts.DwarfDebugFlags, RuntimeVers,
       CGOpts.EnableSplitDwarf ? "" : CGOpts.SplitDwarfFile, EmissionKind,
@@ -2108,6 +2126,7 @@
             : ~1ULL;
     llvm::DIBuilder DIB(CGM.getModule());
     DIB.createCompileUnit(TheCU->getSourceLanguage(),
+                          // TODO: Support "Source" from external AST providers?
                           DIB.createFile(Mod.getModuleName(), Mod.getPath()),
                           TheCU->getProducer(), true, StringRef(), 0,
                           Mod.getASTFile(), llvm::DICompileUnit::FullDebug,
Index: cfe/trunk/lib/Driver/ToolChains/AMDGPU.h
===================================================================
--- cfe/trunk/lib/Driver/ToolChains/AMDGPU.h
+++ cfe/trunk/lib/Driver/ToolChains/AMDGPU.h
@@ -56,7 +56,7 @@
 public:
   AMDGPUToolChain(const Driver &D, const llvm::Triple &Triple,
                   const llvm::opt::ArgList &Args);
-  unsigned GetDefaultDwarfVersion() const override { return 2; }
+  unsigned GetDefaultDwarfVersion() const override { return 5; }
   bool IsIntegratedAssemblerDefault() const override { return true; }
   llvm::opt::DerivedArgList *
   TranslateArgs(const llvm::opt::DerivedArgList &Args, StringRef BoundArch,
Index: cfe/trunk/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- cfe/trunk/lib/Driver/ToolChains/Clang.cpp
+++ cfe/trunk/lib/Driver/ToolChains/Clang.cpp
@@ -3024,6 +3024,18 @@
   if (DebugInfoKind == codegenoptions::LimitedDebugInfo && NeedFullDebug)
     DebugInfoKind = codegenoptions::FullDebugInfo;
 
+  if (Args.hasFlag(options::OPT_gembed_source, options::OPT_gno_embed_source, false)) {
+    // Source embedding is a vendor extension to DWARF v5. By now we have
+    // checked if a DWARF version was stated explicitly, and have otherwise
+    // fallen back to the target default, so if this is still not at least 5 we
+    // emit an error.
+    if (DWARFVersion < 5)
+      D.Diag(diag::err_drv_argument_only_allowed_with)
+          << Args.getLastArg(options::OPT_gembed_source)->getAsString(Args)
+          << "-gdwarf-5";
+    CmdArgs.push_back("-gembed-source");
+  }
+
   RenderDebugEnablingArgs(Args, CmdArgs, DebugInfoKind, DWARFVersion,
                           DebuggerTuning);
 
Index: cfe/trunk/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- cfe/trunk/lib/Frontend/CompilerInvocation.cpp
+++ cfe/trunk/lib/Frontend/CompilerInvocation.cpp
@@ -545,6 +545,7 @@
   Opts.DebugTypeExtRefs = Args.hasArg(OPT_dwarf_ext_refs);
   Opts.DebugExplicitImport = Args.hasArg(OPT_dwarf_explicit_import);
   Opts.DebugFwdTemplateParams = Args.hasArg(OPT_debug_forward_template_params);
+  Opts.EmbedSource = Args.hasArg(OPT_gembed_source);
 
   for (const auto &Arg : Args.getAllArgValues(OPT_fdebug_prefix_map_EQ))
     Opts.DebugPrefixMap.insert(StringRef(Arg).split('='));
Index: cfe/trunk/test/CodeGen/Inputs/debug-info-embed-source.c
===================================================================
--- cfe/trunk/test/CodeGen/Inputs/debug-info-embed-source.c
+++ cfe/trunk/test/CodeGen/Inputs/debug-info-embed-source.c
@@ -0,0 +1 @@
+void foo() { }
Index: cfe/trunk/test/CodeGen/debug-info-embed-source.c
===================================================================
--- cfe/trunk/test/CodeGen/debug-info-embed-source.c
+++ cfe/trunk/test/CodeGen/debug-info-embed-source.c
@@ -0,0 +1,5 @@
+// RUN: %clang_cc1                -debug-info-kind=limited -emit-llvm %p/Inputs/debug-info-embed-source.c -o - | FileCheck %s --check-prefix=NOEMBED
+// RUN: %clang_cc1 -gembed-source -debug-info-kind=limited -emit-llvm %p/Inputs/debug-info-embed-source.c -o - | FileCheck %s --check-prefix=EMBED
+
+// NOEMBED-NOT: !DIFile({{.*}}source:
+// EMBED: !DIFile({{.*}}source: "void foo() { }\0A"
Index: cfe/trunk/test/Driver/amdgpu-toolchain.c
===================================================================
--- cfe/trunk/test/Driver/amdgpu-toolchain.c
+++ cfe/trunk/test/Driver/amdgpu-toolchain.c
@@ -3,4 +3,4 @@
 // AS_LINK: ld.lld{{.*}} "-shared"
 
 // RUN: %clang -### -g -target amdgcn--amdhsa -mcpu=kaveri %s 2>&1 | FileCheck -check-prefix=DWARF_VER %s
-// DWARF_VER: "-dwarf-version=2"
+// DWARF_VER: "-dwarf-version=5"
Index: cfe/trunk/test/Driver/debug-options.c
===================================================================
--- cfe/trunk/test/Driver/debug-options.c
+++ cfe/trunk/test/Driver/debug-options.c
@@ -245,3 +245,13 @@
 // RUN: %clang -###                  %s 2>&1 | FileCheck -check-prefix=NOMACRO %s
 // MACRO: "-debug-info-macro"
 // NOMACRO-NOT: "-debug-info-macro"
+//
+// RUN: %clang -### -gdwarf-5 -gembed-source %s 2>&1 | FileCheck -check-prefix=GEMBED_5 %s
+// RUN: %clang -### -gdwarf-2 -gembed-source %s 2>&1 | FileCheck -check-prefix=GEMBED_2 %s
+// RUN: %clang -### -gdwarf-5 -gno-embed-source %s 2>&1 | FileCheck -check-prefix=NOGEMBED_5 %s
+// RUN: %clang -### -gdwarf-2 -gno-embed-source %s 2>&1 | FileCheck -check-prefix=NOGEMBED_2 %s
+//
+// GEMBED_5:  "-gembed-source"
+// GEMBED_2:  error: invalid argument '-gembed-source' only allowed with '-gdwarf-5'
+// NOGEMBED_5-NOT:  "-gembed-source"
+// NOGEMBED_2-NOT:  error: invalid argument '-gembed-source' only allowed with '-gdwarf-5'