diff --git a/klog.go b/klog.go
index 628117e6d..d608b5bf6 100644
--- a/klog.go
+++ b/klog.go
@@ -396,45 +396,51 @@ type flushSyncWriter interface {
 	io.Writer
 }
 
-// init sets up the defaults.
+var logging = loggingT{
+	settings: settings{
+		contextualLoggingEnabled: true,
+	},
+}
+var commandLine flag.FlagSet
+
+// init sets up the defaults and creates command line flags.
 func init() {
+	commandLine.StringVar(&logging.logDir, "log_dir", "", "If non-empty, write log files in this directory (no effect when -logtostderr=true)")
+	commandLine.StringVar(&logging.logFile, "log_file", "", "If non-empty, use this log file (no effect when -logtostderr=true)")
+	commandLine.Uint64Var(&logging.logFileMaxSizeMB, "log_file_max_size", 1800,
+		"Defines the maximum size a log file can grow to (no effect when -logtostderr=true). Unit is megabytes. "+
+			"If the value is 0, the maximum file size is unlimited.")
+	commandLine.BoolVar(&logging.toStderr, "logtostderr", true, "log to standard error instead of files")
+	commandLine.BoolVar(&logging.alsoToStderr, "alsologtostderr", false, "log to standard error as well as files (no effect when -logtostderr=true)")
+	logging.setVState(0, nil, false)
+	commandLine.Var(&logging.verbosity, "v", "number for the log level verbosity")
+	commandLine.BoolVar(&logging.addDirHeader, "add_dir_header", false, "If true, adds the file directory to the header of the log messages")
+	commandLine.BoolVar(&logging.skipHeaders, "skip_headers", false, "If true, avoid header prefixes in the log messages")
+	commandLine.BoolVar(&logging.oneOutput, "one_output", false, "If true, only write logs to their native severity level (vs also writing to each lower severity level; no effect when -logtostderr=true)")
+	commandLine.BoolVar(&logging.skipLogHeaders, "skip_log_headers", false, "If true, avoid headers when opening log files (no effect when -logtostderr=true)")
 	logging.stderrThreshold = severityValue{
 		Severity: severity.ErrorLog, // Default stderrThreshold is ERROR.
 	}
-	logging.setVState(0, nil, false)
-	logging.logDir = ""
-	logging.logFile = ""
-	logging.logFileMaxSizeMB = 1800
-	logging.toStderr = true
-	logging.alsoToStderr = false
-	logging.skipHeaders = false
-	logging.addDirHeader = false
-	logging.skipLogHeaders = false
-	logging.oneOutput = false
+	commandLine.Var(&logging.stderrThreshold, "stderrthreshold", "logs at or above this threshold go to stderr when writing to files and stderr (no effect when -logtostderr=true or -alsologtostderr=false)")
+	commandLine.Var(&logging.vmodule, "vmodule", "comma-separated list of pattern=N settings for file-filtered logging")
+	commandLine.Var(&logging.traceLocation, "log_backtrace_at", "when logging hits line file:N, emit a stack trace")
+
 	logging.flushD = newFlushDaemon(logging.lockAndFlushAll, nil)
 }
 
 // InitFlags is for explicitly initializing the flags.
+// It may get called repeatedly for different flagsets, but not
+// twice for the same one. May get called concurrently
+// to other goroutines using klog. However, only some flags
+// may get set concurrently (see implementation).
 func InitFlags(flagset *flag.FlagSet) {
 	if flagset == nil {
 		flagset = flag.CommandLine
 	}
 
-	flagset.StringVar(&logging.logDir, "log_dir", logging.logDir, "If non-empty, write log files in this directory (no effect when -logtostderr=true)")
-	flagset.StringVar(&logging.logFile, "log_file", logging.logFile, "If non-empty, use this log file (no effect when -logtostderr=true)")
-	flagset.Uint64Var(&logging.logFileMaxSizeMB, "log_file_max_size", logging.logFileMaxSizeMB,
-		"Defines the maximum size a log file can grow to (no effect when -logtostderr=true). Unit is megabytes. "+
-			"If the value is 0, the maximum file size is unlimited.")
-	flagset.BoolVar(&logging.toStderr, "logtostderr", logging.toStderr, "log to standard error instead of files")
-	flagset.BoolVar(&logging.alsoToStderr, "alsologtostderr", logging.alsoToStderr, "log to standard error as well as files (no effect when -logtostderr=true)")
-	flagset.Var(&logging.verbosity, "v", "number for the log level verbosity")
-	flagset.BoolVar(&logging.addDirHeader, "add_dir_header", logging.addDirHeader, "If true, adds the file directory to the header of the log messages")
-	flagset.BoolVar(&logging.skipHeaders, "skip_headers", logging.skipHeaders, "If true, avoid header prefixes in the log messages")
-	flagset.BoolVar(&logging.oneOutput, "one_output", logging.oneOutput, "If true, only write logs to their native severity level (vs also writing to each lower severity level; no effect when -logtostderr=true)")
-	flagset.BoolVar(&logging.skipLogHeaders, "skip_log_headers", logging.skipLogHeaders, "If true, avoid headers when opening log files (no effect when -logtostderr=true)")
-	flagset.Var(&logging.stderrThreshold, "stderrthreshold", "logs at or above this threshold go to stderr when writing to files and stderr (no effect when -logtostderr=true or -alsologtostderr=false)")
-	flagset.Var(&logging.vmodule, "vmodule", "comma-separated list of pattern=N settings for file-filtered logging")
-	flagset.Var(&logging.traceLocation, "log_backtrace_at", "when logging hits line file:N, emit a stack trace")
+	commandLine.VisitAll(func(f *flag.Flag) {
+		flagset.Var(f.Value, f.Name, f.Usage)
+	})
 }
 
 // Flush flushes all pending log I/O.
@@ -549,12 +555,6 @@ type loggingT struct {
 	vmap map[uintptr]Level
 }
 
-var logging = loggingT{
-	settings: settings{
-		contextualLoggingEnabled: true,
-	},
-}
-
 // setVState sets a consistent state for V logging.
 // l.mu is held.
 func (l *loggingT) setVState(verbosity Level, filter []modulePat, setFilter bool) {