diff --git a/bin/pt-stalk b/bin/pt-stalk
index 86c59367..81fb387b 100755
--- a/bin/pt-stalk
+++ b/bin/pt-stalk
@@ -1032,25 +1032,34 @@ stalk() {
       # Run the trigger which returns the value of whatever is being
       # checked.  When the value is > --threshold for at least --cycle
       # consecutive times, start collecting.
-      local value=$($TRIGGER_FUNCTION $OPT_VARIABLE)
-      local trg_exit_status=$?
+      if [ "$OPT_STALK" ]; then
+         local value=$($TRIGGER_FUNCTION $OPT_VARIABLE)
+         local trg_exit_status=$?
 
-      if [ -z "$value" ]; then
-         # No value.  Maybe we failed to connect to MySQL?
-         warn "Detected value is empty; something failed?  Trigger exit status: $trg_exit_status"
-         matched=""
-         cycles_true=0
-      elif [ $value -gt $OPT_THRESHOLD ]; then
-         matched="yes"
-         cycles_true=$(($cycles_true + 1))
-      else
-         matched=""
-         cycles_true=0
+         if [ -z "$value" ]; then
+            # No value.  Maybe we failed to connect to MySQL?
+            warn "Detected value is empty; something failed?  Trigger exit status: $trg_exit_status"
+            matched=""
+            cycles_true=0
+         elif [ $value -gt $OPT_THRESHOLD ]; then
+            matched="yes"
+            cycles_true=$(($cycles_true + 1))
+         else
+            matched=""
+            cycles_true=0
+         fi
+
+         local msg="Check results: $OPT_VARIABLE=$value, matched=${matched:-no}, cycles_true=$cycles_true"
+         log "$msg"
+      elif [ "$OPT_COLLECT" ]; then
+         # Make the next if condition true.
+         matched=1
+         cycles_true=$OPT_CYCLES
+
+         local msg="Not stalking; collect triggered immediately"
+         log "$msg"
       fi
 
-      local msg="Check results: $OPT_VARIABLE=$value, matched=${matched:-no}, cycles_true=$cycles_true"
-      log "$msg"
-
       if [ "$matched" -a $cycles_true -ge $OPT_CYCLES ]; then 
          # ##################################################################
          # Start collecting, maybe.
@@ -1085,7 +1094,6 @@ stalk() {
                log "pt-stalk ran with $RAN_WITH" >> "$OPT_DEST/$prefix-trigger"
                last_prefix="$prefix"
 
-
                # Fork and background the collect subroutine which will
                # run for --run-time seconds.  We (the parent) sleep
                # while its collecting (hopefully --sleep is longer than
@@ -1166,6 +1174,14 @@ if    [ "${0##*/}" = "$TOOL" ] \
       option_error "Invalid --function value: $OPT_FUNCTION"
    fi
 
+   if [ -z "$OPT_STALK" -a "$OPT_COLLECT" ]; then
+      # Not stalking; do immediate collect once.
+      OPT_ITERATIONS=1
+      OPT_CYCLES=0
+      OPT_SLEEP=0
+      OPT_INTERVAL=0
+   fi
+
    usage_or_errors "$0"
    po_status=$?
    rm_tmpdir
@@ -1206,7 +1222,7 @@ if    [ "${0##*/}" = "$TOOL" ] \
       fi
    fi
 
-   if [ "$OPT_DAEMONIZE" ]; then
+   if [ "$OPT_STALK" -a "$OPT_DAEMONIZE" ]; then
       # Check access to the --log file.
       touch "$OPT_LOG" || die "Cannot write to --log $OPT_LOG"
 
@@ -1226,7 +1242,7 @@ if    [ "${0##*/}" = "$TOOL" ] \
       # use $! to get the PID of the child we just forked.
       echo "$!" > "$OPT_PID"
    else
-      make_pid_file "$OPT_PID" $$
+      [ "$OPT_STALK" ] && make_pid_file "$OPT_PID" $$
       main "$@"
    fi
 fi
@@ -1360,6 +1376,8 @@ default: yes; negatable: yes
 Collect system information.  You can negate this option to make the tool watch
 the system but not actually gather any diagnostic data.
 
+See also L<"--stalk">.
+
 =item --collect-gdb
 
 Collect GDB stacktraces.  This is achieved by attaching to MySQL and printing
@@ -1583,6 +1601,22 @@ continuously, which might be a problem if the collection process is intrusive.
 It also prevents filling up the disk or gathering too much data to analyze
 reasonably.
 
+=item --stalk
+
+default: yes; negatable: yes
+
+Watch the server and wait for the trigger to occur.  You can negate this option
+to make the tool immediately gather any diagnostic data once and exit.  This is
+useful if a problem is already happening, but pt-stalk is not running, so
+you only want to collect diagnostic data.
+
+If this option is negate, L<"--daemonize">, L<"--log">, L<"--pid">, and other
+stalking-related options have no effect; the tool simply collects diagnostic
+data and exits.  Safeguard options, like L<"--disk-bytes-free"> and
+L<"--disk-pct-free">, are still respected.
+
+See also L<"--collect">.
+
 =item --threshold
 
 type: int; default: 25
diff --git a/lib/PerconaTest.pm b/lib/PerconaTest.pm
index 8c076840..0731896b 100644
--- a/lib/PerconaTest.pm
+++ b/lib/PerconaTest.pm
@@ -294,6 +294,16 @@ sub wait_for_files {
    );
 }
 
+sub wait_for_sh {
+   my ($cmd) = @_;
+   return wait_until(
+      sub {
+         my $retval = system("$cmd 2>/dev/null");
+         return $retval >> 8 == 0 ? 1 : 0;
+      }
+   );
+};
+
 sub _read {
    my ( $fh ) = @_;
    return <$fh>;
diff --git a/t/pt-stalk/pt-stalk.t b/t/pt-stalk/pt-stalk.t
index 83d180d7..7e44dea8 100644
--- a/t/pt-stalk/pt-stalk.t
+++ b/t/pt-stalk/pt-stalk.t
@@ -24,7 +24,7 @@ if ( !$dbh ) {
    plan skip_all => 'Cannot connect to sandbox master';
 }
 else {
-   plan tests => 21;
+   plan tests => 25;
 }
 
 my $cnf      = "/tmp/12345/my.sandbox.cnf";
@@ -155,7 +155,7 @@ is(
    "Collect ran for --run-time"
 );
 
-$output = `ps x | grep -v grep | grep 'pt-stalk pt-stalk --iterations 1 --dest $dest'`;
+$output = `ps x | grep -v grep | grep 'pt-stalk --iterations 1'`;
 is(
    $output,
    "",
@@ -202,7 +202,7 @@ ok(
    "No files collected"
 );
 
-$output = `ps x | grep -v grep | grep 'pt-stalk pt-stalk --iterations 1 --dest $dest'`;
+$output = `ps x | grep -v grep | grep 'pt-stalk --no-collect'`;
 is(
    $output,
    "",
@@ -237,6 +237,45 @@ like(
 diag(`rm $ENV{HOME}/.pt-stalk.conf`);
 diag(`cp $ENV{HOME}/.pt-stalk.conf.original $ENV{HOME}/.pt-stalk.conf 2>/dev/null`);
 
+# #############################################################################
+# Don't stalk, just collect.
+# #############################################################################
+diag(`rm $pid_file 2>/dev/null`);
+diag(`rm $log_file 2>/dev/null`);
+diag(`rm $dest/*   2>/dev/null`);
+
+$retval = system("$trunk/bin/pt-stalk --no-stalk --run-time 2 --dest $dest --prefix nostalk -- --defaults-file=$cnf >$log_file 2>&1");
+
+PerconaTest::wait_for_files("$dest/nostalk-trigger");
+$output = `cat $dest/nostalk-trigger`;
+like(
+   $output,
+   qr/Not stalking/,
+   "Not stalking, collect triggered"
+);
+
+PerconaTest::wait_for_files("$dest/nostalk-df");
+PerconaTest::wait_for_sh("test \$(grep -c '^TS' $dest/nostalk-df) -ge 2");
+chomp($output = `grep -c '^TS' $dest/nostalk-df`);
+is(
+   $output,
+   2,
+   "Not stalking, collect ran for --run-time"
+);
+
+is(
+   `cat $dest/nostalk-hostname`,
+   `hostname`,
+   "Not stalking, collect gathered data"
+);
+
+$output = `ps x | grep -v grep | grep 'pt-stalk --no-stalk'`;
+is(
+   $output,
+   "",
+   "Not stalking, pt-stalk is not running"
+);
+
 # #############################################################################
 # Done.
 # #############################################################################