diff --git a/llvm/lib/MC/MCParser/ELFAsmParser.cpp b/llvm/lib/MC/MCParser/ELFAsmParser.cpp
--- a/llvm/lib/MC/MCParser/ELFAsmParser.cpp
+++ b/llvm/lib/MC/MCParser/ELFAsmParser.cpp
@@ -339,6 +339,11 @@
     case 'G':
       flags |= ELF::SHF_GROUP;
       break;
+    case 'l':
+      if (TT.getArch() != Triple::x86_64)
+        return -1U;
+      flags |= ELF::SHF_X86_64_LARGE;
+      break;
     case 'R':
       if (TT.isOSSolaris())
         flags |= ELF::SHF_SUNW_NODISCARD;
diff --git a/llvm/test/MC/ELF/section-flags-unknown.s b/llvm/test/MC/ELF/section-flags-unknown.s
--- a/llvm/test/MC/ELF/section-flags-unknown.s
+++ b/llvm/test/MC/ELF/section-flags-unknown.s
@@ -1,5 +1,6 @@
 ## Some section flags are processor-specific. Reject them for other targets.
-# RUN: not llvm-mc -triple=x86_64 %s -o /dev/null 2>&1 | FileCheck %s --implicit-check-not=error:
+# REQUIRES: riscv-registered-target
+# RUN: not llvm-mc -triple=riscv32 %s -o /dev/null 2>&1 | FileCheck %s --implicit-check-not=error:
 
 # CHECK: {{.*}}.s:[[# @LINE+1]]:34: error: unknown flag
 .section XCORE_SHF_CP_SECTION,"c",@progbits
@@ -12,3 +13,6 @@
 
 # CHECK: {{.*}}.s:[[# @LINE+1]]:30: error: unknown flag
 .section SHF_ARM_PURECODE,"y",@progbits
+
+# CHECK: {{.*}}.s:[[# @LINE+1]]:30: error: unknown flag
+.section SHF_X86_64_LARGE,"l",@progbits
diff --git a/llvm/test/MC/ELF/section.s b/llvm/test/MC/ELF/section.s
--- a/llvm/test/MC/ELF/section.s
+++ b/llvm/test/MC/ELF/section.s
@@ -268,6 +268,14 @@
 // CHECK-NEXT:       SHF_WRITE
 // CHECK-NEXT:     ]
 
+.section .large,"l"
+// CHECK:        Section {
+// CHECK:          Name: .large
+// CHECK-NEXT:     Type: SHT_PROGBITS
+// CHECK-NEXT:     Flags [
+// CHECK-NEXT:       SHF_X86_64_LARGE
+// CHECK-NEXT:     ]
+
 // Test SHT_LLVM_ODRTAB
 
 .section .odrtab,"e",@llvm_odrtab