diff --git a/firefox.spec b/firefox.spec
index 0c801a4..2da2b38 100644
--- a/firefox.spec
+++ b/firefox.spec
@@ -40,7 +40,7 @@ ExcludeArch: s390x
 # on other arches.
 %ifarch x86_64 aarch64
 %if %{release_build}
-%global build_with_pgo    0
+%global build_with_pgo    1
 %else
 %global build_with_pgo    0
 %endif
@@ -163,6 +163,7 @@ Patch47:        fedora-shebang-build.patch
 Patch48:        build-arm-wasm.patch
 Patch49:        build-arm-libaom.patch
 #Patch50:        Bug-1610814-Fix-NEON-compile-error-with-gcc-and-RGB-.patch
+Patch51:        mozilla-1640982.patch
 
 # Fedora specific patches
 Patch215:        firefox-enable-addons.patch
@@ -367,6 +368,7 @@ This package contains results of tests executed during build.
 %patch48 -p1 -b .build-arm-wasm
 %patch49 -p1 -b .build-arm-libaom
 #%patch50 -p1 -b .build-arm-SwizzleNEON
+%patch51 -p1 -b .mozilla-1640982
 
 # Fedora patches
 %patch215 -p1 -b .addons
diff --git a/mozilla-1640982.patch b/mozilla-1640982.patch
new file mode 100644
index 0000000..b63ba3b
--- /dev/null
+++ b/mozilla-1640982.patch
@@ -0,0 +1,16 @@
+diff --git a/config/makefiles/rust.mk b/config/makefiles/rust.mk
+--- a/config/makefiles/rust.mk
++++ b/config/makefiles/rust.mk
+@@ -61,7 +61,11 @@
+ # Enable link-time optimization for release builds, but not when linking
+ # gkrust_gtest.
+ ifeq (,$(findstring gkrust_gtest,$(RUST_LIBRARY_FILE)))
++# Pass -Clto for older versions of rust, and CARGO_PROFILE_RELEASE_LTO=true
++# for newer ones that support it. Combining the latter with -Clto works, so
++# set both everywhere.
+ cargo_rustc_flags += -Clto
++export CARGO_PROFILE_RELEASE_LTO=true
+ endif
+ endif
+ endif
+