build: Enable function sections and data sections during LTO.

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index 6a495cc2a82b8b2500a5c7c0c5398b7389c8f0a3..092991d12fd13afbc88f722b4d17d9f4f1285006 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -512,12 +512,22 @@ config("compiler") {
       ldflags += [ "-Wl,-all_load" ]
     }
 
-    # Allows the linker to apply ICF to the LTO object file. Also, when
-    # targeting ARM, without this flag, LTO produces a .text section that is
-    # larger than the maximum call displacement, preventing the linker from
-    # relocating calls (http://llvm.org/PR22999).
+    # Allows the linker to apply --gc-sections and ICF to the LTO object file.
+    # Also, when targeting ARM, without this flag, LTO produces a .text section
+    # that is larger than the maximum call displacement, preventing the linker
+    # from relocating calls (http://llvm.org/PR22999).
     if (is_linux) {
-      ldflags += [ "-Wl,-plugin-opt,-function-sections" ]
+      if (use_lld) {
+        ldflags += [
+          "-Wl,-mllvm,-function-sections",
+          "-Wl,-mllvm,-data-sections",
+        ]
+      } else {
+        ldflags += [
+          "-Wl,-plugin-opt,-function-sections",
+          "-Wl,-plugin-opt,-data-sections",
+        ]
+      }
     }
   }