diff --git a/configs/macos/mozconfig b/configs/macos/mozconfig
index 0df4c6858..ad0e77fb8 100644
--- a/configs/macos/mozconfig
+++ b/configs/macos/mozconfig
@@ -29,27 +29,22 @@ if test "$SURFER_COMPAT" = "x86_64"; then
   if test "$ZEN_RELEASE"; then
     ac_add_options --enable-wasm-avx
     ac_add_options --enable-optimize="-march=nehalem -mtune=haswell -O3 -w"
-
-    export CFLAGS="-O3 -march=nehalem"
-    export CPPFLAGS="-O3 -march=nehalem"
-    export CXXFLAGS="-O3 -march=nehalem"
-    export LDFLAGS="-Wl,-O3 -march=nehalem"
-    export RUSTFLAGS="-Ctarget-cpu=nehalem"
   fi
 else
   ac_add_options --enable-clang-plugin
   ac_add_options --target=aarch64-apple-darwin
 
   if test "$ZEN_RELEASE"; then
-    ac_add_options --enable-optimize="-O3 -mcpu=apple-m1 -march=armv8.3-a+simd"
+    ac_add_options --enable-optimize="-O3 -mcpu=apple-m1"
 
     # As of Clang 13, the default is -mcpu=apple-m1 when using a aarch64-apple-macos target,
     # but we're using apple64-apple-darwin, which defaults to -mcpu=apple-a7, which disables
     # a bunch of # performance-enabling CPU features.
-    export CFLAGS="-O3 -march=armv8.3-a+simd -mcpu=apple-m1"
-    export CPPFLAGS="-O3 -march=armv8.3-a+simd -mcpu=apple-m1"
-    export CXXFLAGS="-O3 -march=armv8.3-a+simd -mcpu=apple-m1"
-    export LDFLAGS="-Wl,-O3 -march=armv8.3-a+simd -mcpu=apple-m1"
-    export RUSTFLAGS="-C target-feature=+v8.3a -Ctarget-cpu=apple-m1"
+    # TODO: We'll want to switch to aarch64-apple-macos eventually.
+    export CFLAGS="$CFLAGS -mcpu=apple-m1"
+    export CXXFLAGS="$CXXFLAGS -mcpu=apple-m1"
+
+    # Keep using ld64 on PGO/LTO builds because of performance regressions when using lld.
+    ac_add_options --enable-linker=ld64
   fi
 fi
diff --git a/configs/windows/mozconfig b/configs/windows/mozconfig
index df0b0ef71..685d9605b 100644
--- a/configs/windows/mozconfig
+++ b/configs/windows/mozconfig
@@ -36,8 +36,8 @@ if test "$SURFER_COMPAT" = "x86_64"; then
 
   ac_add_options --enable-optimize="-O3 -w -ftree-vectorize -mfpmath=sse -mprfchw -msse3 -mcx16 -msahf"
 
-  export LDFLAGS="-Wl,-O3"
-  export RUSTFLAGS="-Clink-args=--icf=safe"
+  export LDFLAGS="$LDFLAGS -Wl,-O3"
+  export RUSTFLAGS="$RUSTFLAGS -Clink-args=--icf=safe"
 elif test "$SURFER_COMPAT" = "aarch64"; then
   ac_add_options --target=aarch64-pc-windows-msvc
   ac_add_options --enable-eme=widevine