diff --git a/nodist/code_coverage b/nodist/code_coverage
index 18e8ac368..9762b5331 100755
--- a/nodist/code_coverage
+++ b/nodist/code_coverage
@@ -6,7 +6,9 @@ use warnings;
 use Cwd;
 use File::Copy qw(cp);
 use File::Path qw(mkpath);
+use FindBin qw($RealBin);
 use Getopt::Long;
+use Parallel::Forker;
 use IO::File;
 use Pod::Usage;
 use strict;
@@ -19,10 +21,16 @@ our $Remove_Gcda_Regexp;
 our @Remove_Sources;
 our @Source_Globs;
 
+our $Fork = new Parallel::Forker (use_sig_child=>1);
+$SIG{CHLD} = sub { Parallel::Forker::sig_child($Fork); };
+$SIG{TERM} = sub { $Fork->kill_tree_all('TERM') if $Fork && $Fork->in_parent; die "Quitting...\n"; };
+
 #======================================================================
 # main
 
-our $Opt_Stage = 0;
+our $Opt_Fastcov = 0;  # out of memory
+our $opt_stages = '';
+our %Opt_Stages;
 
 autoflush STDOUT 1;
 autoflush STDERR 1;
@@ -30,12 +38,29 @@ Getopt::Long::config("no_auto_abbrev");
 if (! GetOptions(
           "debug"       => sub { $Debug = 1; },
           "<>"          => sub { die "%Error: Unknown parameter: $_[0]\n"; },
-          "stage=i"     => \$Opt_Stage,  # starting stage number
+          "stages=s"    => \$opt_stages,  # starting stage number
           "stop!"       => \$Opt_Stop,  # stop/do not stop on error in tests
     )) {
     die "%Error: Bad usage, try 'install_test --help'\n";
 }
 
+{
+    my $start = 0;
+    my $end = 99;
+    if ($opt_stages && $opt_stages =~ /^(\d+)$/) {
+        $start = $end = $1;
+    } elsif ($opt_stages && $opt_stages =~ /^(\d+)-(\d+$)$/) {
+        $start = $1; $end = $2;
+    } elsif ($opt_stages && $opt_stages =~ /^-(\d+$)$/) {
+        $end = $1;
+    } elsif ($opt_stages && $opt_stages =~ /^(\d+)-$/) {
+        $start = $1;
+    } elsif ($opt_stages) {
+        die "%Error: --stages not understood: $opt_stages,";
+    }
+    for (my $n = $start; $n <= $end; ++$n) { $Opt_Stages{$n} = 1; }
+}
+
 test();
 exit(0);
 
@@ -45,11 +70,18 @@ sub test {
     -r "nodist/code_coverage.dat" or die "%Error: Run from the top of the verilator kit,";
     require "./nodist/code_coverage.dat";
 
-    if ($Opt_Stage <= 0) {
+    if ($Opt_Stages{1}) {
         travis_fold_start("configure");
-        print "Stage 0: configure (coverage on)\n";
+        print "Stage 1: configure (coverage on)\n";
         run("make distclean || true");
+        run("autoconf");
         run("./configure --enable-longtests CXX='g++ --coverage'");
+        travis_fold_end();
+    }
+
+    if ($Opt_Stages{2}) {
+        travis_fold_start("build");
+        print "Stage 2: build\n";
         run("make -k");
         # The optimized versions will not collect good coverage, overwrite them
         run("cp bin/verilator_bin_dbg bin/verilator_bin");
@@ -57,9 +89,9 @@ sub test {
         travis_fold_end();
     }
 
-    if ($Opt_Stage <= 1) {
+    if ($Opt_Stages{3}) {
         travis_fold_start("test");
-        print "Stage 1: make examples (with coverage on)\n";
+        print "Stage 3: make examples (with coverage on)\n";
         run("make examples");
         run("make test_regress"
             . ($Opt_Stop ? '' : ' || true'));
@@ -67,9 +99,9 @@ sub test {
     }
 
     my $cc_dir = "nodist/obj_dir/coverage";
-    if ($Opt_Stage <= 2) {
+    if ($Opt_Stages{4}) {
         travis_fold_start("info");
-        print "Stage 2: Create info files under $cc_dir\n";
+        print "Stage 4: Create info files under $cc_dir\n";
         mkpath($cc_dir);
         mkpath("$cc_dir/info");
         my $dats = `find . -print | grep .gcda`;
@@ -77,7 +109,6 @@ sub test {
         foreach my $dat (split '\n', $dats) {
             $dats{$dat} = 1;
         }
-        my %dirs;
         my %gcnos;
         foreach my $dat (sort keys %dats) {
             (my $gcno = $dat) =~ s!\.gcda$!.gcno!;
@@ -105,29 +136,71 @@ sub test {
                     warn "MISSING .gcno for a .gcda: $gcno\n";
                 }
             }
-            (my $dir = $dat) =~ s!/[^/]+$!!;
-            $dirs{$dir} = 1;
-        }
-        foreach my $dir (sort keys %dirs) {
-            (my $outname = $dir) =~ s![^a-zA-Z0-9]+!_!g;
-            run("cd $cc_dir/info ; lcov -c -d ../../../../$dir -o app_test_${outname}.info");
         }
         travis_fold_end();
     }
 
-    if ($Opt_Stage <= 3) {
+    my $Opt_Fastcov = 0;
+    if ($Opt_Stages{5} && $Opt_Fastcov) {
+        travis_fold_start("fastcov");
+        #Runs out of memory:
+        #run("${RealBin}/fastcov.py -o $cc_dir/app_total.info");
+        #Drops a lot of coverage:
+        my $dats = `find . -print | grep .gcda`;
+        my %dirs;
+        my @dats = sort(split '\n', $dats);
+        foreach my $dat (@dats) {
+            (my $dir = $dat) =~ s!/[^/]+$!!;
+            $dirs{$dir} = 1;
+        }
+        my $chunk = 0;
+        my $comb = "";
+        foreach my $dat (@dats) {
+            $comb .= " -f ../../../../$dat";
+            # Need to batch to avoid memory limit
+            if (length($comb) > 20000 || $dat eq $dats[$#dats]) {
+                run("cd $cc_dir/info ; ${RealBin}/fastcov.py ${comb} --exclude /usr -o app_chunk_${chunk}.info");
+                $comb = "";
+                ++$chunk;
+            }
+        }
+
+        travis_fold_end();
+    }
+
+    if ($Opt_Stages{5} && !$Opt_Fastcov) {
+        travis_fold_start("infos");
+        print "Stage 5: make infos\n";
+        my $dats = `find . -print | grep .gcda`;
+        my %dirs;
+        foreach my $dat (split '\n', $dats) {
+            (my $dir = $dat) =~ s!/[^/]+$!!;
+            $dirs{$dir} = 1;
+        }
+
+        foreach my $dir (sort keys %dirs) {
+            (my $outname = $dir) =~ s![^a-zA-Z0-9]+!_!g;
+            $Fork->schedule(run_on_start => sub {
+                run("cd $cc_dir/info ; lcov -c -d ../../../../$dir --exclude /usr -o app_test_${outname}.info");
+                            })->run;
+        }
+        $Fork->wait_all;
+        travis_fold_end();
+    }
+
+    if ($Opt_Stages{6}) {
         travis_fold_start("clone");
         # lcov doesn't have a control file to override single lines, so replicate the sources
-        print "Stage 3: Clone sources under $cc_dir\n";
+        print "Stage 6: Clone sources under $cc_dir\n";
         clone_sources($cc_dir);
         travis_fold_end();
     }
 
-    if ($Opt_Stage <= 4) {
+    if ($Opt_Stages{8}) {
         travis_fold_start("copy");
-        print "Stage 4: Copy .gcno files\n";
+        print "Stage 8: Copy .gcno files\n";
         my $dats = `find . -print | grep .gcno`;
-        foreach my $dat (split '\n', $dats) {
+        foreach my $dat (sort (split '\n', $dats)) {
             next if $dat =~ /$cc_dir/;
             my $outdat = $cc_dir."/".$dat;
             #print "cp $dat, $outdat);\n";
@@ -136,14 +209,14 @@ sub test {
         travis_fold_end();
     }
 
-    if ($Opt_Stage <= 5) {
+    if ($Opt_Stages{10}) {
         travis_fold_start("combine");
-        print "Stage 5: Combine data files\n";
+        print "Stage 10: Combine data files\n";
         run("cd $cc_dir ; lcov -c -i -d src/obj_dbg -o app_base.info");
         run("cd $cc_dir ; lcov -a app_base.info -o app_total.info");
         my $infos = `cd $cc_dir ; find info -print | grep .info`;
         my $comb = "";
-        my @infos = (split /\n/, $infos);
+        my @infos = (sort (split /\n/, $infos));
         foreach my $info (@infos) {
             $comb .= " -a $info";
             # Need to batch them to avoid overrunning shell command length limit
@@ -155,9 +228,9 @@ sub test {
         travis_fold_end();
     }
 
-    if ($Opt_Stage <= 6) {
+    if ($Opt_Stages{12}) {
         travis_fold_start("filter");
-        print "Stage 6: Filter processed source files\n";
+        print "Stage 12: Filter processed source files\n";
         my $cmd = '';
         foreach my $glob (@Remove_Sources) {
             $cmd .= " '$glob'";
@@ -166,24 +239,24 @@ sub test {
         travis_fold_end();
     }
 
-    if ($Opt_Stage <= 8) {
+    if ($Opt_Stages{17}) {
         travis_fold_start("report");
-        print "Stage 7: Create HTML\n";
+        print "Stage 17: Create HTML\n";
         cleanup_abs_paths($cc_dir, "$cc_dir/app_total.info", "$cc_dir/app_total.info");
         run("cd $cc_dir ; genhtml app_total.info --demangle-cpp"
             ." --rc lcov_branch_coverage=1 --rc genhtml_hi_limit=100 --output-directory html");
         travis_fold_end();
     }
 
-    if ($Opt_Stage <= 9) {
+    if ($Opt_Stages{18}) {
         travis_fold_start("upload");
-        print "Stage 9: Upload\n";
+        print "Stage 18: Upload\n";
         my $cmd = "bash <(curl -s https://codecov.io/bash) -f $cc_dir/app_total.info";
         print "print: Not running: $cmd\n";
         travis_fold_end();
     }
 
-    if ($Opt_Stage <= 9) {
+    if ($Opt_Stages{19}) {
         print "*-* All Finished *-*\n";
     }
 }