diff --git a/src/cmd/compile/internal/ssa/compile.go b/src/cmd/compile/internal/ssa/compile.go
index bd90235682204d..2f15cfd1e7aa98 100644
--- a/src/cmd/compile/internal/ssa/compile.go
+++ b/src/cmd/compile/internal/ssa/compile.go
@@ -192,29 +192,55 @@ var BuildDump string // name of function to dump after initial build of ssa
 func PhaseOption(phase, flag string, val int, valString string) string {
 	if phase == "help" {
 		lastcr := 0
-		phasenames := "check, all, build, intrinsics"
+		phasenames := "    check, all, build, intrinsics"
 		for _, p := range passes {
 			pn := strings.Replace(p.name, " ", "_", -1)
 			if len(pn)+len(phasenames)-lastcr > 70 {
-				phasenames += "\n"
+				phasenames += "\n    "
 				lastcr = len(phasenames)
 				phasenames += pn
 			} else {
 				phasenames += ", " + pn
 			}
 		}
-		return "" +
-			`GcFlag -d=ssa/<phase>/<flag>[=<value>|<function_name>]
-<phase> is one of:
+		return `PhaseOptions usage:
+
+    go tool compile -d=ssa/<phase>/<flag>[=<value>|<function_name>]
+
+where:
+
+- <phase> is one of:
 ` + phasenames + `
-<flag> is one of on, off, debug, mem, time, test, stats, dump
-<value> defaults to 1
-<function_name> is required for "dump", specifies name of function to dump after <phase>
-Except for dump, output is directed to standard out; dump appears in a file.
+
+- <flag> is one of:
+    on, off, debug, mem, time, test, stats, dump
+
+- <value> defaults to 1
+
+- <function_name> is required for the "dump" flag, and specifies the
+  name of function to dump after <phase>
+
 Phase "all" supports flags "time", "mem", and "dump".
-Phases "intrinsics" supports flags "on", "off", and "debug".
-Interpretation of the "debug" value depends on the phase.
-Dump files are named <phase>__<function_name>_<seq>.dump.
+Phase "intrinsics" supports flags "on", "off", and "debug".
+
+If the "dump" flag is specified, the output is written on a file named
+<phase>__<function_name>_<seq>.dump; otherwise it is directed to stdout.
+
+Examples:
+
+    -d=ssa/check/on
+enables checking after each phase
+
+    -d=ssa/all/time
+enables time reporting for all phases
+
+    -d=ssa/prove/debug=2
+sets debugging level to 2 in the prove pass
+
+Multiple flags can be passed at once, by separating them with
+commas. For example:
+
+    -d=ssa/check/on,ssa/all/time
 `
 	}