diff --git a/lld/MachO/Config.h b/lld/MachO/Config.h
--- a/lld/MachO/Config.h
+++ b/lld/MachO/Config.h
@@ -68,6 +68,9 @@
   unknown,
   none,
   safe,
+#if defined(__FACEBOOK__)
+  fbsafe,
+#endif
   all,
 };
 
diff --git a/lld/MachO/Driver.cpp b/lld/MachO/Driver.cpp
--- a/lld/MachO/Driver.cpp
+++ b/lld/MachO/Driver.cpp
@@ -772,6 +772,9 @@
   auto icfLevel = StringSwitch<ICFLevel>(icfLevelStr)
                       .Cases("none", "", ICFLevel::none)
                       .Case("safe", ICFLevel::safe)
+#if defined(__FACEBOOK__)
+                      .Case("fbsafe", ICFLevel::fbsafe)
+#endif
                       .Case("all", ICFLevel::all)
                       .Default(ICFLevel::unknown);
   if (icfLevel == ICFLevel::unknown) {
@@ -1774,6 +1777,10 @@
     if (config->icfLevel != ICFLevel::none) {
       if (config->icfLevel == ICFLevel::safe)
         markAddrSigSymbols();
+#if defined(__FACEBOOK__)
+      else if (config->icfLevel == ICFLevel::fbsafe)
+        markAddrSigSymbolsViaRelocations();
+#endif
       foldIdenticalSections(/*onlyCfStrings=*/false);
     } else if (config->dedupLiterals) {
       foldIdenticalSections(/*onlyCfStrings=*/true);
diff --git a/lld/MachO/ICF.h b/lld/MachO/ICF.h
--- a/lld/MachO/ICF.h
+++ b/lld/MachO/ICF.h
@@ -20,6 +20,17 @@
 void markSymAsAddrSig(Symbol *s);
 void foldIdenticalSections(bool onlyCfStrings);
 
+#if defined(__FACEBOOK__)
+// This marks symbols as addrsig not by using `__llvm_addrsig` contents, but by
+// looking for relocations that suggest a given function's address is being
+// taken. This is the approach ld64 takes, and its results are far less
+// conservative than what `-faddrsig` emits. Ideally, we'd like to make
+// `-faddrsig` less conservative and use that, but this is a good temporary
+// solution.
+// NOTE: Only implemented for arm64 targets right now.
+void markAddrSigSymbolsViaRelocations();
+#endif
+
 } // namespace lld::macho
 
 #endif
diff --git a/lld/MachO/ICF.cpp b/lld/MachO/ICF.cpp
--- a/lld/MachO/ICF.cpp
+++ b/lld/MachO/ICF.cpp
@@ -394,6 +394,23 @@
   }
 }
 
+#if defined(__FACEBOOK__)
+void macho::markAddrSigSymbolsViaRelocations() {
+  TimeTraceScope timeScope("Mark addrsig symbols via relocations");
+  assert(target->cpuType == MachO::CPU_TYPE_ARM64);
+  for (ConcatInputSection *isec : inputSections) {
+    for (const Reloc &r : isec->relocs) {
+      if (r.type != MachO::ARM64_RELOC_PAGEOFF12)
+        continue;
+      if (auto *sym = r.referent.dyn_cast<Symbol *>())
+        if (auto *d = dyn_cast<Defined>(sym))
+          if (d->isec && isCodeSection(d->isec) && !d->weakDefCanBeHidden)
+            markSymAsAddrSig(sym);
+    }
+  }
+}
+#endif
+
 void macho::foldIdenticalSections(bool onlyCfStrings) {
   TimeTraceScope timeScope("Fold Identical Code Sections");
   // The ICF equivalence-class segregation algorithm relies on pre-computed
diff --git a/lld/test/FBMachO/icf-fbsafe.s b/lld/test/FBMachO/icf-fbsafe.s
new file mode 100644
--- /dev/null
+++ b/lld/test/FBMachO/icf-fbsafe.s
@@ -0,0 +1,31 @@
+# REQUIRES: aarch64
+# RUN: rm -rf %t; split-file %s %t
+# RUN: llvm-mc -filetype=obj -triple=arm64-apple-darwin %t/test.s -o %t/test.o
+# RUN: %lld -lSystem -dylib -arch arm64 %t/test.o -o %t/test --icf=fbsafe
+# RUN: llvm-objdump --macho --syms %t/test | FileCheck %s
+
+# CHECK-DAG: [[#%.16x,NOT_ADDRSIG:]] l     F __TEXT,__text _not_addrsig
+# CHECK-DAG: [[#NOT_ADDRSIG]]        l     F __TEXT,__text _autohide_addrsig
+# CHECK-DAG: [[#NOT_ADDRSIG-4]]      l     F __TEXT,__text _addrsig
+
+#--- test.s
+
+_address_taker:
+  ldr x1, [x1, _addrsig@PAGEOFF]
+  ldr x1, [x1, _autohide_addrsig@PAGEOFF]
+
+_caller:
+  bl _not_addrsig
+
+_addrsig:
+  nop
+
+.globl _autohide_addrsig
+.weak_def_can_be_hidden _autohide_addrsig
+_autohide_addrsig:
+  nop
+
+_not_addrsig:
+  nop
+
+.subsections_via_symbols