Index: ELF/Writer.cpp
===================================================================
--- ELF/Writer.cpp
+++ ELF/Writer.cpp
@@ -1519,6 +1519,15 @@
         sec->type == SHT_ARM_EXIDX)
       continue;
 
+    for (InputSection *s: sections) {
+      InputSection *link = s->getLinkOrderDep();
+      if (!link->getParent())
+        error(toString(s) + ": sh_link points to discarded section " +
+              toString(link));
+    }
+    if (errorCount())
+      continue;
+
     llvm::stable_sort(sections, compareByFilePosition);
 
     for (int i = 0, n = sections.size(); i < n; ++i)
@@ -1894,6 +1903,8 @@
   // SHFLinkOrder processing must be processed after relative section placements are
   // known but before addresses are allocated.
   resolveShfLinkOrder();
+  if (errorCount())
+    return;
 
   // This is used to:
   // 1) Create "thunks":
Index: test/ELF/gc-sections-metadata-err.s
===================================================================
--- /dev/null
+++ test/ELF/gc-sections-metadata-err.s
@@ -0,0 +1,37 @@
+# REQUIRES: x86
+
+## Error if the linked-to section of an input section is discarded.
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
+# RUN: not ld.lld --gc-sections --print-gc-sections %t.o -o %t 2>&1 | FileCheck %s
+
+# CHECK:      removing unused section {{.*}}:(.foo0)
+# CHECK-NEXT: error: {{.*}}.o:(.bar): sh_link points to discarded section {{.*}}.o:(.foo0)
+# CHECK-NEXT: error: {{.*}}.o:(.baz): sh_link points to discarded section {{.*}}.o:(.foo0)
+
+.globl _start
+_start:
+  call .foo1
+  call bar0
+  call bar1
+  call baz0
+  call baz1
+
+.section .foo0,"a"
+.section .foo1,"a"
+
+## The linked-to section of the first input section is discarded.
+.section .bar,"ao",@progbits,.foo0,unique,0
+bar0:
+.byte 0
+.section .bar,"ao",@progbits,.foo1,unique,1
+bar1:
+.byte 1
+
+## Test another case: the linked-to section of the second input section is discarded.
+.section .baz,"ao",@progbits,.foo1,unique,0
+baz0:
+.byte 0
+.section .baz,"ao",@progbits,.foo0,unique,1
+baz1:
+.byte 1