diff --git a/include/clang/Driver/CC1Options.td b/include/clang/Driver/CC1Options.td
index f3c6d11..2511dfb 100644
--- a/include/clang/Driver/CC1Options.td
+++ b/include/clang/Driver/CC1Options.td
@@ -178,6 +178,8 @@
   HelpText<"Print source range spans in numeric form">;
 def fdiagnostics_show_option : Flag<"-fdiagnostics-show-option">,
   HelpText<"Print diagnostic name with mappable diagnostics">;
+def ftabstop : Separate<"-ftabstop">, MetaVarName<"<N>">,
+  HelpText<"Set the tab stop distance.">;
 def fmessage_length : Separate<"-fmessage-length">, MetaVarName<"<N>">,
   HelpText<"Format message diagnostics so that they fit within N columns or fewer, when possible.">;
 def fcolor_diagnostics : Flag<"-fcolor-diagnostics">,
diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index 247e1f5..955d98e 100644
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -345,6 +345,7 @@
 def fstack_protector : Flag<"-fstack-protector">, Group<f_Group>;
 def fstrict_aliasing : Flag<"-fstrict-aliasing">, Group<clang_ignored_f_Group>;
 def fsyntax_only : Flag<"-fsyntax-only">, Flags<[DriverOption]>;
+def ftabstop_EQ : Joined<"-ftabstop=">, Group<f_Group>;
 def ftemplate_depth_ : Joined<"-ftemplate-depth-">, Group<f_Group>;
 def fterminated_vtables : Flag<"-fterminated-vtables">, Group<f_Group>;
 def ftime_report : Flag<"-ftime-report">, Group<f_Group>;
diff --git a/include/clang/Frontend/DiagnosticOptions.h b/include/clang/Frontend/DiagnosticOptions.h
index 6346dc0..0220e64 100644
--- a/include/clang/Frontend/DiagnosticOptions.h
+++ b/include/clang/Frontend/DiagnosticOptions.h
@@ -35,6 +35,9 @@
                                  /// diagnostics, indicated by markers in the
                                  /// input source file.
 
+  /// The distance between tab stops.
+  unsigned TabStop;
+
   /// Column limit for formatting message diagnostics, or 0 if unused.
   unsigned MessageLength;
 
@@ -49,6 +52,7 @@
 public:
   DiagnosticOptions() {
     IgnoreWarnings = 0;
+    TabStop = 8;
     MessageLength = 0;
     NoRewriteMacros = 0;
     Pedantic = 0;
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index bf59abc..8c10b4d 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -935,6 +935,11 @@
     CmdArgs.push_back(A->getValue(Args));
   }
 
+  if (Arg *A = Args.getLastArg(options::OPT_ftabstop_EQ)) {
+    CmdArgs.push_back("-ftabstop");
+    CmdArgs.push_back(A->getValue(Args));
+  }
+
   // Pass -fmessage-length=.
   CmdArgs.push_back("-fmessage-length");
   if (Arg *A = Args.getLastArg(options::OPT_fmessage_length_EQ)) {
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index 8817469..375c75c 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -222,6 +222,10 @@
     Res.push_back("-verify");
   if (Opts.ShowOptionNames)
     Res.push_back("-fdiagnostics-show-option");
+  if (Opts.TabStop != 8) {
+    Res.push_back("-ftabstop");
+    Res.push_back(llvm::utostr(Opts.TabStop));
+  }
   if (Opts.MessageLength) {
     Res.push_back("-fmessage-length");
     Res.push_back(llvm::utostr(Opts.MessageLength));
@@ -804,6 +808,7 @@
   Opts.ShowOptionNames = Args.hasArg(OPT_fdiagnostics_show_option);
   Opts.ShowSourceRanges = Args.hasArg(OPT_fdiagnostics_print_source_range_info);
   Opts.VerifyDiagnostics = Args.hasArg(OPT_verify);
+  Opts.TabStop = getLastArgIntValue(Args, OPT_ftabstop, 8, Diags);
   Opts.MessageLength = getLastArgIntValue(Args, OPT_fmessage_length, 0, Diags);
   Opts.DumpBuildInformation = getLastArgValue(Args, OPT_dump_build_information);
   Opts.Warnings = getAllArgValues(Args, OPT_W);
diff --git a/lib/Frontend/TextDiagnosticPrinter.cpp b/lib/Frontend/TextDiagnosticPrinter.cpp
index 61f8a70..c27d112 100644
--- a/lib/Frontend/TextDiagnosticPrinter.cpp
+++ b/lib/Frontend/TextDiagnosticPrinter.cpp
@@ -378,9 +378,10 @@
     // Replace this tab with at least one space.
     SourceLine[i] = ' ';
 
+    unsigned TabStop = DiagOpts->TabStop > 0 ? DiagOpts->TabStop : 8;
     // Compute the number of spaces we need to insert.
-    unsigned NumSpaces = ((i+8)&~7) - (i+1);
-    assert(NumSpaces < 8 && "Invalid computation of space amt");
+    unsigned NumSpaces = ((i+TabStop)/TabStop * TabStop) - (i+1);
+    assert(NumSpaces < TabStop && "Invalid computation of space amt");
 
     // Insert spaces into the SourceLine.
     SourceLine.insert(i+1, NumSpaces, ' ');