diff --git a/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchELFObjectWriter.cpp b/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchELFObjectWriter.cpp
--- a/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchELFObjectWriter.cpp
+++ b/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchELFObjectWriter.cpp
@@ -59,7 +59,7 @@
   case FK_Data_4:
     return IsPCRel ? ELF::R_LARCH_32_PCREL : ELF::R_LARCH_32;
   case FK_Data_8:
-    return ELF::R_LARCH_64;
+    return IsPCRel ? ELF::R_LARCH_64_PCREL : ELF::R_LARCH_64;
   case LoongArch::fixup_loongarch_b16:
     return ELF::R_LARCH_B16;
   case LoongArch::fixup_loongarch_b21:
diff --git a/llvm/test/MC/LoongArch/Relocations/sub-expr.s b/llvm/test/MC/LoongArch/Relocations/sub-expr.s
new file mode 100644
--- /dev/null
+++ b/llvm/test/MC/LoongArch/Relocations/sub-expr.s
@@ -0,0 +1,19 @@
+# RUN: llvm-mc --filetype=obj --triple=loongarch64 %s -o %t
+# RUN: llvm-readobj -r %t | FileCheck %s
+
+## Check that subtraction expressions emit R_LARCH_32_PCREL and R_LARCH_64_PCREL relocations.
+
+## TODO: 1- or 2-byte data relocations are not supported for now.
+
+.section sx
+x:
+nop
+
+.data
+.8byte x-.   # CHECK: 0x0 R_LARCH_64_PCREL sx 0x0
+.8byte y-.   # CHECK: 0x8 R_LARCH_64_PCREL sy 0x0
+.4byte x-.   # CHECK: 0x10 R_LARCH_32_PCREL sx 0x0
+.4byte y-.   # CHECK: 0x14 R_LARCH_32_PCREL sy 0x0
+
+.section sy
+y: