diff --git a/build/autoconf/sanitize.m4 b/build/autoconf/sanitize.m4
index 8b18cd5bc7..4f038ccb6f 100644
--- a/build/autoconf/sanitize.m4
+++ b/build/autoconf/sanitize.m4
@@ -80,6 +80,40 @@ if test -n "$MOZ_TSAN"; then
 fi
 AC_SUBST(MOZ_TSAN)
 
+dnl ========================================================
+dnl = Use Leak Sanitizer
+dnl ========================================================
+MOZ_ARG_ENABLE_BOOL(leak-sanitizer,
+[  --enable-leak-sanitizer       Enable Leak Sanitizer (default=no)],
+   MOZ_LSAN=1,
+   MOZ_LSAN= )
+if test -n "$MOZ_LSAN"; then
+    MOZ_LLVM_HACKS=1
+    LDFLAGS="-fsanitize=leak $LDFLAGS"
+    AC_DEFINE(MOZ_LSAN)
+    MOZ_PATH_PROG(LLVM_SYMBOLIZER, llvm-symbolizer)
+fi
+AC_SUBST(MOZ_LSAN)
+
+dnl ========================================================
+dnl = Use Undefined Behavior Sanitizer
+dnl ========================================================
+MOZ_ARG_ENABLE_BOOL(undefined-sanitizer,
+[  --enable-undefined-sanitizer       Enable Undefined Behavior Sanitizer (default=no)],
+   MOZ_UBSAN=1,
+   MOZ_UBSAN= )
+if test -n "$MOZ_UBSAN"; then
+    MOZ_LLVM_HACKS=1
+    CFLAGS="-fsanitize=undefined $CFLAGS"
+    CXXFLAGS="-fsanitize=undefined $CXXFLAGS"
+    if test -z "$CLANG_CL"; then
+        LDFLAGS="-fsanitize=undefined $LDFLAGS"
+    fi
+    AC_DEFINE(MOZ_UBSAN)
+    MOZ_PATH_PROG(LLVM_SYMBOLIZER, llvm-symbolizer)
+fi
+AC_SUBST(MOZ_UBSAN)
+
 # The LLVM symbolizer is used by all sanitizers
 AC_SUBST(LLVM_SYMBOLIZER)
 
diff --git a/build/moz.build b/build/moz.build
index f1a5bf75b0..85f97aebac 100644
--- a/build/moz.build
+++ b/build/moz.build
@@ -68,7 +68,7 @@ OBJDIR_FILES += ['!/dist/bin/.gdbinit_python']
 if CONFIG['MOZ_ASAN'] and CONFIG['MOZ_CLANG_RT_ASAN_LIB_PATH']:
     FINAL_TARGET_FILES += [CONFIG['MOZ_CLANG_RT_ASAN_LIB_PATH']]
 if CONFIG['LLVM_SYMBOLIZER']:
-    FINAL_TARGET_FILES += [CONFIG['LLVM_SYMBOLIZER']]
+    FINAL_TARGET_FILES += ['/' + CONFIG['LLVM_SYMBOLIZER']]
 
 if CONFIG['MOZ_APP_BASENAME']:
     FINAL_TARGET_PP_FILES += ['application.ini']
diff --git a/build/moz.configure/old.configure b/build/moz.configure/old.configure
index 527e3afd50..9b611d429b 100644
--- a/build/moz.configure/old.configure
+++ b/build/moz.configure/old.configure
@@ -196,6 +196,7 @@ def old_configure_options(*options):
     '--enable-ios-target',
     '--enable-jitspew',
     '--enable-js-lto',
+    '--enable-leak-sanitizer',
     '--enable-libjpeg-turbo',
     '--enable-libproxy',
     '--enable-llvm-hacks',
@@ -246,6 +247,7 @@ def old_configure_options(*options):
     '--enable-thread-sanitizer',
     '--enable-trace-logging',
     '--enable-ui-locale',
+    '--enable-undefined-sanitizer',
     '--enable-universalchardet',
     '--enable-updater',
     '--enable-url-classifier',