Index: lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.cpp
===================================================================
--- lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.cpp
+++ lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.cpp
@@ -121,9 +121,11 @@
 }
 
 /// \brief R_AARCH64_ADR_PREL_LO21 - S + A - P
-static void relocR_AARCH64_ADR_PREL_LO21(uint8_t *location, uint64_t P,
-                                         uint64_t S, int64_t A) {
+static std::error_code relocR_AARCH64_ADR_PREL_LO21(uint8_t *location, uint64_t P,
+                                                    uint64_t S, int64_t A) {
   uint64_t result = (S + A) - P;
+  if (!isInt<20>(result))
+    return make_out_of_range_reloc_error();
   uint32_t immlo = result & 0x3;
   uint32_t immhi = result & 0x1FFFFC;
   immlo = immlo << 29;
@@ -136,6 +138,7 @@
         llvm::dbgs() << " immlo: " << Twine::utohexstr(immlo);
         llvm::dbgs() << " result: " << Twine::utohexstr(result) << "\n");
   write32le(location, immlo | immhi | read32le(location));
+  return std::error_code();
   // TODO: Make sure this is correct!
 }
 
@@ -400,8 +403,7 @@
   case R_AARCH64_ADR_PREL_PG_HI21:
     return relocR_AARCH64_ADR_PREL_PG_HI21(loc, reloc, target, addend);
   case R_AARCH64_ADR_PREL_LO21:
-    relocR_AARCH64_ADR_PREL_LO21(loc, reloc, target, addend);
-    break;
+    return relocR_AARCH64_ADR_PREL_LO21(loc, reloc, target, addend);
   case R_AARCH64_ADD_ABS_LO12_NC:
     relocR_AARCH64_ADD_ABS_LO12_NC(loc, reloc, target, addend);
     break;
Index: test/elf/AArch64/rel-adr_prel_lo21-overflow.test
===================================================================
--- /dev/null
+++ test/elf/AArch64/rel-adr_prel_lo21-overflow.test
@@ -0,0 +1,45 @@
+# Check handling of R_AARCH64_ADR_PREL_PG_HI21 relocation.
+# RUN: yaml2obj -format=elf %s > %t-obj
+# RUN: not lld -flavor gnu -target arm64 -o %t-exe %t-obj
+
+# CHECK: Relocation out of range in file {{.*}}: reference from _start+0 to data1+1048577 of type 274 (R_AARCH64_ADR_PREL_LO21) 
+
+!ELF
+FileHeader: !FileHeader
+  Class: ELFCLASS64
+  Data: ELFDATA2LSB
+  Type: ET_REL
+  Machine: EM_AARCH64
+
+Sections:
+- Name: .text
+  Type: SHT_PROGBITS
+  Content: "00000090"
+  AddressAlign: 16
+  Flags: [SHF_ALLOC, SHF_EXECINSTR]
+
+- Name: .data
+  Type: SHT_PROGBITS
+  Content: "00000000"
+  AddressAlign: 16
+  Flags: [SHF_ALLOC, SHF_WRITE]
+
+- Name: .rela.text
+  Type: SHT_RELA
+  Info: .text
+  AddressAlign: 8
+  Relocations:
+    - Offset: 0x0
+      Symbol: data1
+      Type: R_AARCH64_ADR_PREL_LO21
+      Addend: 0x100001
+
+Symbols:
+  Global:
+    - Name: _start
+      Section: .text
+      Value: 0x0
+      Size: 4
+    - Name: data1
+      Section: .data
+      Size: 8
Index: test/elf/AArch64/rel-adr_prel_lo21.test
===================================================================
--- /dev/null
+++ test/elf/AArch64/rel-adr_prel_lo21.test
@@ -0,0 +1,49 @@
+# Check handling of R_AARCH64_ADR_PREL_PG_HI21 relocation.
+# RUN: yaml2obj -format=elf %s > %t-obj
+# RUN: lld -flavor gnu -target arm64 -o %t-exe %t-obj
+# RUN: llvm-objdump -d -t %t-exe | FileCheck %s
+
+# CHECK:       Disassembly of section .text:
+# CHECK-NEXT:  _start:
+# CHECK-NEXT:  4001b0:	80 75 00 90   adrp  x0, #15400960
+# CHECK:       SYMBOL TABLE:
+# CHECK:       00401060 g  .data  00000004 data1
+
+!ELF
+FileHeader: !FileHeader
+  Class: ELFCLASS64
+  Data: ELFDATA2LSB
+  Type: ET_REL
+  Machine: EM_AARCH64
+
+Sections:
+- Name: .text
+  Type: SHT_PROGBITS
+  Content: "00000090"
+  AddressAlign: 16
+  Flags: [SHF_ALLOC, SHF_EXECINSTR]
+- Name: .data
+  Type: SHT_PROGBITS
+  Content: "00000000"
+  AddressAlign: 16
+  Flags: [SHF_ALLOC, SHF_WRITE]
+
+- Name: .rela.text
+  Type: SHT_RELA
+  Info: .text
+  AddressAlign: 8
+  Relocations:
+    - Offset: 0x0
+      Symbol: data1
+      Type: R_AARCH64_ADR_PREL_LO21
+      Addend: 0
+
+Symbols:
+  Global:
+    - Name: _start
+      Section: .text
+      Value: 0x0
+      Size: 4
+    - Name: data1
+      Section: .data
+      Size: 8