diff --git a/src/clang_options_data.zig b/src/clang_options_data.zig
index bd1237bc00..632857920b 100644
--- a/src/clang_options_data.zig
+++ b/src/clang_options_data.zig
@@ -75,8 +75,22 @@ flagpd1("M"),
     .psl = false,
 },
 flagpd1("Mach"),
-flagpd1("O0"),
-flagpd1("O4"),
+.{
+    .name = "O0",
+    .syntax = .flag,
+    .zig_equivalent = .optimize,
+    .pd1 = true,
+    .pd2 = false,
+    .psl = false,
+},
+.{
+    .name = "O4",
+    .syntax = .flag,
+    .zig_equivalent = .optimize,
+    .pd1 = true,
+    .pd2 = false,
+    .psl = false,
+},
 .{
     .name = "O",
     .syntax = .flag,
@@ -2163,7 +2177,7 @@ flagpd1("fno-ident"),
 .{
     .name = "Os",
     .syntax = .flag,
-    .zig_equivalent = .other,
+    .zig_equivalent = .optimize,
     .pd1 = true,
     .pd2 = false,
     .psl = true,
@@ -3148,7 +3162,14 @@ flagpd1("fxray-link-deps"),
 flagpd1("fzero-initialized-in-bss"),
 flagpd1("fzvector"),
 flagpd1("g0"),
-flagpd1("g1"),
+.{
+    .name = "g1",
+    .syntax = .flag,
+    .zig_equivalent = .debug,
+    .pd1 = true,
+    .pd2 = false,
+    .psl = false,
+},
 flagpd1("g2"),
 flagpd1("g3"),
 .{
@@ -3189,7 +3210,14 @@ flagpd1("ggdb3"),
 flagpd1("ggnu-pubnames"),
 flagpd1("ginline-line-tables"),
 flagpd1("gline-directives-only"),
-flagpd1("gline-tables-only"),
+.{
+    .name = "gline-tables-only",
+    .syntax = .flag,
+    .zig_equivalent = .debug,
+    .pd1 = true,
+    .pd2 = false,
+    .psl = false,
+},
 flagpd1("glldb"),
 flagpd1("gmlt"),
 flagpd1("gmodules"),
@@ -5363,7 +5391,7 @@ jspd1("iquote"),
 joinpd1("weak-l"),
 .{
     .name = "Ofast",
-    .syntax = .joined,
+    .syntax = .flag,
     .zig_equivalent = .optimize,
     .pd1 = true,
     .pd2 = false,
diff --git a/src/main.zig b/src/main.zig
index b89ac3768e..8a3fb72102 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -992,15 +992,20 @@ fn buildOutputType(
                     },
                     .optimize => {
                         // Alright, what release mode do they want?
-                        if (mem.eql(u8, it.only_arg, "Os")) {
+                        const level = if (it.only_arg.len >= 1 and it.only_arg[0] == 'O') it.only_arg[1..] else it.only_arg;
+                        if (mem.eql(u8, level, "s") or
+                            mem.eql(u8, level, "z"))
+                        {
                             optimize_mode = .ReleaseSmall;
-                        } else if (mem.eql(u8, it.only_arg, "O2") or
-                            mem.eql(u8, it.only_arg, "O3") or
-                            mem.eql(u8, it.only_arg, "O4"))
+                        } else if (mem.eql(u8, level, "1") or
+                            mem.eql(u8, level, "2") or
+                            mem.eql(u8, level, "3") or
+                            mem.eql(u8, level, "4") or
+                            mem.eql(u8, level, "fast"))
                         {
                             optimize_mode = .ReleaseFast;
-                        } else if (mem.eql(u8, it.only_arg, "Og") or
-                            mem.eql(u8, it.only_arg, "O0"))
+                        } else if (mem.eql(u8, level, "g") or
+                            mem.eql(u8, level, "0"))
                         {
                             optimize_mode = .Debug;
                         } else {
@@ -1009,8 +1014,13 @@ fn buildOutputType(
                     },
                     .debug => {
                         strip = false;
-                        if (mem.eql(u8, it.only_arg, "-g")) {
+                        if (mem.eql(u8, it.only_arg, "g")) {
                             // We handled with strip = false above.
+                        } else if (mem.eql(u8, it.only_arg, "g1") or
+                            mem.eql(u8, it.only_arg, "gline-tables-only"))
+                        {
+                            // We handled with strip = false above. but we also want reduced debug info.
+                            try clang_argv.append("-gline-tables-only");
                         } else {
                             try clang_argv.appendSlice(it.other_args);
                         }
diff --git a/tools/update_clang_options.zig b/tools/update_clang_options.zig
index 8b7811aa26..9510b6a075 100644
--- a/tools/update_clang_options.zig
+++ b/tools/update_clang_options.zig
@@ -130,6 +130,10 @@ const known_options = [_]KnownOpt{
         .name = "assemble",
         .ident = "asm_only",
     },
+    .{
+        .name = "O0",
+        .ident = "optimize",
+    },
     .{
         .name = "O1",
         .ident = "optimize",
@@ -138,10 +142,20 @@ const known_options = [_]KnownOpt{
         .name = "O2",
         .ident = "optimize",
     },
+    // O3 is only detected from the joined "-O" option
+    .{
+        .name = "O4",
+        .ident = "optimize",
+    },
     .{
         .name = "Og",
         .ident = "optimize",
     },
+    .{
+        .name = "Os",
+        .ident = "optimize",
+    },
+    // Oz is only detected from the joined "-O" option
     .{
         .name = "O",
         .ident = "optimize",
@@ -154,6 +168,14 @@ const known_options = [_]KnownOpt{
         .name = "optimize",
         .ident = "optimize",
     },
+    .{
+        .name = "g1",
+        .ident = "debug",
+    },
+    .{
+        .name = "gline-tables-only",
+        .ident = "debug",
+    },
     .{
         .name = "g",
         .ident = "debug",
@@ -390,6 +412,10 @@ pub fn main() anyerror!void {
             // the only way.
             try stdout.print("flagpsl(\"{}\"),\n", .{name});
         } else if (knownOption(name)) |ident| {
+
+            // Workaround the fact that in 'Options.td'  -Ofast is listed as 'joined'
+            const final_syntax = if (std.mem.eql(u8, name, "Ofast")) .flag else syntax;
+
             try stdout.print(
                 \\.{{
                 \\    .name = "{}",
@@ -400,7 +426,7 @@ pub fn main() anyerror!void {
                 \\    .psl = {},
                 \\}},
                 \\
-            , .{ name, syntax, ident, pd1, pd2, pslash });
+            , .{ name, final_syntax, ident, pd1, pd2, pslash });
         } else if (pd1 and !pd2 and !pslash and syntax == .flag) {
             try stdout.print("flagpd1(\"{}\"),\n", .{name});
         } else if (!pd1 and !pd2 and pslash and syntax == .flag) {