--- ./build/config/compiler/BUILD.gn.orig
+++ ./build/config/compiler/BUILD.gn
@@ -591,24 +591,6 @@
       }
     }
 
-    # TODO(crbug.com/40283598): This causes binary size growth and potentially
-    # other problems.
-    # TODO(crbug.com/40284925): This isn't supported by Cronet's mainline llvm version.
-    if (default_toolchain != "//build/toolchain/cros:target" &&
-        !llvm_android_mainline) {
-      cflags += [
-        "-mllvm",
-        "-split-threshold-for-reg-with-hint=0",
-      ]
-      if (use_thin_lto && is_a_target_toolchain) {
-        if (is_win) {
-          ldflags += [ "-mllvm:-split-threshold-for-reg-with-hint=0" ]
-        } else {
-          ldflags += [ "-Wl,-mllvm,-split-threshold-for-reg-with-hint=0" ]
-        }
-      }
-    }
-
     # TODO(crbug.com/40192287): Investigate why/if this should be needed.
     if (is_win) {
       cflags += [ "/clang:-ffp-contract=off" ]
@@ -1045,20 +1027,6 @@
     # `-nodefaultlibs` from the linker invocation from Rust, which would be used
     # to compile dylibs on Android, such as for constructing unit test APKs.
     "-Cdefault-linker-libraries",
-
-    # To make Rust .d files compatible with ninja
-    "-Zdep-info-omit-d-target",
-
-    # If a macro panics during compilation, show which macro and where it is
-    # defined.
-    "-Zmacro-backtrace",
-
-    # For deterministic builds, keep the local machine's current working
-    # directory from appearing in build outputs.
-    "-Zremap-cwd-prefix=.",
-
-    # We use clang-rt sanitizer runtimes.
-    "-Zexternal-clangrt",
   ]
 
   if (!is_win || force_rustc_color_output) {
@@ -1107,7 +1075,6 @@
 # Don't allow unstable features to be enabled by `#![feature()]` without
 # additional command line flags.
 config("disallow_unstable_features") {
-  rustflags = [ "-Zallow-features=" ]
 }
 
 config("libcxx_hardening") {
@@ -1242,8 +1209,8 @@
       }
     } else if (current_cpu == "arm") {
       if (is_clang && !is_android && !is_nacl && !is_chromeos_device) {
-        cflags += [ "--target=arm-linux-gnueabihf" ]
-        ldflags += [ "--target=arm-linux-gnueabihf" ]
+        cflags += [ "--target=armv7-alpine-linux-musleabihf" ]
+        ldflags += [ "--target=armv7-alpine-linux-musleabihf" ]
       }
       if (!is_nacl) {
         cflags += [
@@ -1257,8 +1224,8 @@
     } else if (current_cpu == "arm64") {
       if (is_clang && !is_android && !is_nacl && !is_fuchsia &&
           !is_chromeos_device) {
-        cflags += [ "--target=aarch64-linux-gnu" ]
-        ldflags += [ "--target=aarch64-linux-gnu" ]
+        cflags += [ "--target=aarch64-alpine-linux-musl" ]
+        ldflags += [ "--target=aarch64-alpine-linux-musl" ]
       }
     } else if (current_cpu == "mipsel" && !is_nacl) {
       ldflags += [ "-Wl,--hash-style=sysv" ]
@@ -2086,7 +2053,7 @@
       defines = [ "_HAS_NODISCARD" ]
     }
   } else {
-    cflags = [ "-Wall" ]
+    cflags = []
     if (is_clang) {
       # Enable extra warnings for chromium_code when we control the compiler.
       cflags += [ "-Wextra" ]
--- ./build/config/rust.gni.orig
+++ ./build/config/rust.gni
@@ -198,13 +198,13 @@
 rust_abi_target = ""
 if (is_linux || is_chromeos) {
   if (current_cpu == "arm64") {
-    rust_abi_target = "aarch64-unknown-linux-gnu"
+    rust_abi_target = "aarch64-alpine-linux-musl"
     cargo_target_abi = ""
   } else if (current_cpu == "x86") {
-    rust_abi_target = "i686-unknown-linux-gnu"
+    rust_abi_target = "i586-alpine-linux-musl"
     cargo_target_abi = ""
   } else if (current_cpu == "x64") {
-    rust_abi_target = "x86_64-unknown-linux-gnu"
+    rust_abi_target = "x86_64-alpine-linux-musl"
     cargo_target_abi = ""
   } else if (current_cpu == "arm") {
     if (arm_float_abi == "hard") {
@@ -214,18 +214,18 @@
     }
     if (arm_arch == "armv7-a" || arm_arch == "armv7") {
       # No way to inform Rust about the -a suffix.
-      rust_abi_target = "armv7-unknown-linux-gnueabi" + float_suffix
+      rust_abi_target = "armv7-alpine-linux-musleabi" + float_suffix
       cargo_target_abi = "eabi" + float_suffix
     } else {
-      rust_abi_target = "arm-unknown-linux-gnueabi" + float_suffix
+      rust_abi_target = "armv6-alpine-linux-musleabi" + float_suffix
       cargo_target_abi = "eabi" + float_suffix
     }
   } else if (current_cpu == "riscv64") {
-    rust_abi_target = "riscv64gc-unknown-linux-gnu"
+    rust_abi_target = "riscv64-alpine-linux-musl"
     cargo_target_abi = ""
   } else {
     # Best guess for other future platforms.
-    rust_abi_target = current_cpu + "-unknown-linux-gnu"
+    rust_abi_target = current_cpu + "-alpine-linux-musl"
     cargo_target_abi = ""
   }
 } else if (is_android) {
--- ./build/config/clang/BUILD.gn.orig
+++ ./build/config/clang/BUILD.gn
@@ -128,14 +128,15 @@
       } else if (is_apple) {
         _dir = "darwin"
       } else if (is_linux || is_chromeos) {
+        _dir = "linux"
         if (current_cpu == "x64") {
-          _dir = "x86_64-unknown-linux-gnu"
+          _suffix = "-x86_64"
         } else if (current_cpu == "x86") {
-          _dir = "i386-unknown-linux-gnu"
+          _suffix = "-i386"
         } else if (current_cpu == "arm") {
-          _dir = "armv7-unknown-linux-gnueabihf"
+          _suffix = "-armhf"
         } else if (current_cpu == "arm64") {
-          _dir = "aarch64-unknown-linux-gnu"
+          _suffix = "-aarch64"
         } else {
           assert(false)  # Unhandled cpu type
         }
--- ./build/config/gcc/BUILD.gn.orig
+++ ./build/config/gcc/BUILD.gn
@@ -32,7 +32,6 @@
 # See http://gcc.gnu.org/wiki/Visibility
 config("symbol_visibility_hidden") {
   cflags = [ "-fvisibility=hidden" ]
-  rustflags = [ "-Zdefault-visibility=hidden" ]
 
   # Visibility attribute is not supported on AIX.
   if (current_os != "aix") {