Index: lld/trunk/ELF/AArch64ErrataFix.cpp
===================================================================
--- lld/trunk/ELF/AArch64ErrataFix.cpp
+++ lld/trunk/ELF/AArch64ErrataFix.cpp
@@ -451,7 +451,7 @@
         continue;
       if (!IsCodeMapSymbol(Def) && !IsDataMapSymbol(Def))
         continue;
-      if (auto *Sec = dyn_cast<InputSection>(Def->Section))
+      if (auto *Sec = dyn_cast_or_null<InputSection>(Def->Section))
         if (Sec->Flags & SHF_EXECINSTR)
           SectionMap[Sec].push_back(Def);
     }
Index: lld/trunk/test/ELF/aarch64-cortex-a53-843419-abs-mapsyms.s
===================================================================
--- lld/trunk/test/ELF/aarch64-cortex-a53-843419-abs-mapsyms.s
+++ lld/trunk/test/ELF/aarch64-cortex-a53-843419-abs-mapsyms.s
@@ -0,0 +1,22 @@
+// REQUIRES: aarch64
+// RUN: llvm-mc -filetype=obj -triple=aarch64-linux-gnu %s -o %t
+// RUN: ld.lld --just-symbols %t -fix-cortex-a53-843419 -o %t.axf
+// RUN: llvm-readobj --symbols %t.axf | FileCheck %s
+
+// Check that we can gracefully handle --just-symbols, which gives a local
+// absolute mapping symbol (with no Section). Previously we assumed that all
+// mapping symbols were defined relative to a section and assert failed.
+
+        .text
+        .global _start
+        .type _start, %function
+_start: ret
+
+// CHECK:     Name: $x.0
+// CHECK-NEXT:     Value: 0x0
+// CHECK-NEXT:     Size: 0
+// CHECK-NEXT:     Binding: Local (0x0)
+// CHECK-NEXT:     Type: None (0x0)
+// CHECK-NEXT:     Other: 0
+// CHECK-NEXT:     Section: Absolute (0xFFF1)
+// CHECK-NEXT:   }