diff --git a/abi_used_libs b/abi_used_libs
--- a/abi_used_libs
+++ b/abi_used_libs
@@ -7,6 +7,8 @@
 libXfixes.so.3
 libXrender.so.1
 libatk-1.0.so.0
+libc++.so.1
+libc++abi.so.1
 libc.so.6
 libcairo-gobject.so.2
 libcairo.so.2
@@ -32,7 +34,6 @@
 libpixman-1.so.0
 libpthread.so.0
 librt.so.1
-libstdc++.so.6
 libxcb-shm.so.0
 libxcb.so.1
 libz.so.1
diff --git a/files/config b/files/config
--- a/files/config
+++ b/files/config
@@ -32,3 +32,10 @@
 
 ac_add_options --enable-system-ffi
 ac_add_options --enable-system-pixman
+
+ac_add_options --enable-linker=lld
+
+# Firefox seems to want libc++ as opposed to libstdc++
+# when building with clang.
+ac_add_options CC="clang -stdlib=libc++"
+ac_add_options CXX="clang++ -stdlib=libc++"
diff --git a/package.yml b/package.yml
--- a/package.yml
+++ b/package.yml
@@ -1,6 +1,6 @@
 name       : firefox
 version    : '84.0'
-release    : 206
+release    : 207
 source     :
     - https://ftp.mozilla.org/pub/firefox/releases/84.0/source/firefox-84.0.source.tar.xz : 23273ef0165b243f5d0908c38e7854d38070282c9b526e8d93b7503cd5f69138
     - https://getsol.us/sources/mozilla/firefox-84.0-langpacks.tar.xz : 90709b5b165e2c8f41a9643b3993d2d5728051d3c93f1d777c4425dd3005b10e
@@ -11,7 +11,7 @@
 summary    : Firefox web browser
 description: |
     Mozilla Firefox is an open-source web browser, designed for standards compliance, performance and portability. Its functionality can be enhanced via a plethora of extensions.
-clang      : no
+clang      : yes
 builddeps  :
     - pkgconfig(alsa)
     - pkgconfig(dbus-glib-1)
@@ -41,6 +41,7 @@
     export MOZ_NOSPAM=1
     export MACH_USE_SYSTEM_PYTHON=1
     export MOZBUILD_STATE_PATH=$PWD
+    export LDFLAGS="${LDFLAGS/--copy-dt-needed-entries/}" # not supported by lld
 setup      : |
     cp $pkgfiles/{google-safebrowsing,mozilla}-api-key .
     cp $pkgfiles/config .mozconfig
@@ -49,8 +50,25 @@
     echo "ac_add_options --with-google-safebrowsing-api-keyfile=${workdir}/google-safebrowsing-api-key" >> .mozconfig
     ./mach configure
 build      : |
-    xvfb-run -a -n 55 -s "-screen 0 1024x768x24 -ac +extension GLX +render -noreset" ./mach build
-    ./mach buildsymbols
+    # Instrument build
+    echo "ac_add_options --enable-profile-generate=cross" >> .mozconfig
+    ./mach build
+
+    # Package and run automated benchmarks for profiling
+    ./mach package
+    LLVM_PROFDATA=llvm-profdata JARLOG_FILE="$PWD/jarlog" xvfb-run -s "-screen 0 1920x1080x24 -ac +extension GLX +render -noreset" \
+    ./mach python build/pgo/profileserver.py
+
+    # Clean for rebuild
+    ./mach clobber
+
+    # Profile use build and enable lto
+    sed -i '/--enable-profile-generate=cross/d' .mozconfig
+    echo "ac_add_options --enable-lto=cross" >> .mozconfig
+    echo "ac_add_options --enable-profile-use=cross" >> .mozconfig
+    echo "ac_add_options --with-pgo-profile-path=${PWD@Q}/merged.profdata" >> .mozconfig
+    echo "ac_add_options --with-pgo-jarlog=${PWD@Q}/jarlog" >> .mozconfig
+    ./mach build
 install    : |
     # Install locales first
     langpackdir="$installdir/%libdir%/firefox/browser/extensions"
diff --git a/pspec_x86_64.xml b/pspec_x86_64.xml
--- a/pspec_x86_64.xml
+++ b/pspec_x86_64.xml
@@ -2,8 +2,8 @@
     <Source>
         <Name>firefox</Name>
         <Packager>
-            <Name>Joshua Strobl</Name>
-            <Email>joshua@getsol.us</Email>
+            <Name>Joey Riches</Name>
+            <Email>josephriches@gmail.com</Email>
         </Packager>
         <License>GPL-2.0-or-later</License>
         <License>MPL-2.0</License>
@@ -173,12 +173,12 @@
         </Files>
     </Package>
     <History>
-        <Update release="206">
-            <Date>2020-12-15</Date>
+        <Update release="207">
+            <Date>2020-12-18</Date>
             <Version>84.0</Version>
             <Comment>Packaging update</Comment>
-            <Name>Joshua Strobl</Name>
-            <Email>joshua@getsol.us</Email>
+            <Name>Joey Riches</Name>
+            <Email>josephriches@gmail.com</Email>
         </Update>
     </History>
 </PISI>
\ No newline at end of file