diff --git a/lld/ELF/Arch/RISCV.cpp b/lld/ELF/Arch/RISCV.cpp
--- a/lld/ELF/Arch/RISCV.cpp
+++ b/lld/ELF/Arch/RISCV.cpp
@@ -605,6 +605,62 @@
   }
 }
 
+// Relax R_RISCV_PCREL_HI20 and R_RISCV_PCREL_LO12_(I|S) pair form auipc+add to
+// lui+add.
+static void relaxPcrel(InputSection &sec, size_t i, uint64_t loc, Relocation &r,
+                       uint32_t &remove) {
+  const Symbol &sym = *r.sym;
+  const uint64_t dest =
+      (r.expr == R_PLT_PC ? sym.getPltVA() : sym.getVA()) + r.addend;
+  const int64_t displace = dest - loc;
+
+  // This relaxation is useless in general, because it does not lessen code
+  // size, so perform it only if pcrel is out of range.
+  if (isInt<32>(displace))
+    return;
+
+  // lui + add could only reference 2GiB from zero.
+  if (!isInt<32>(dest))
+    return;
+
+  // auipc rd, 0 => lui rd, 0
+  const uint64_t auipc = read32le(sec.content().data() + r.offset);
+  const uint32_t rd = extractBits(auipc, 11, 7);
+  sec.relaxAux->writes.push_back(0x37 | rd << 7); // lui
+  sec.relaxAux->relocTypes[i] = R_RISCV_HI20;
+
+  MutableArrayRef<Relocation> rels = sec.relocs();
+
+  // R_RISCV...LO12_(I|S) counterpart.
+  auto &LoRel = rels[i + 2];
+
+  //  R_RISCV_PCREL_HI20/R_RISCV_PCREL_LO12_(I|S) pair
+  //  is a bit weird, because lower part of relocation
+  //  references special symbol in location of auipc instruction
+  //  rather than the actual relocating symbol.
+  //  That's why symbol of lower relocation should be substituted
+  //  during relaxation process.
+  //
+  //  ...
+  //  .Lpcrel_hi0:
+  //      auipc   a0, %pcrel_hi(foo)
+  //      addi    a0, a0, %pcrel_lo(.Lpcrel_hi0)
+  //  ...
+  //
+  LoRel.sym = r.sym;
+
+  r.expr = R_ABS;
+  LoRel.expr = r.expr;
+
+  switch (LoRel.type) {
+  case R_RISCV_PCREL_LO12_I:
+    sec.relaxAux->relocTypes[i + 2] = R_RISCV_LO12_I;
+    break;
+  case R_RISCV_PCREL_LO12_S:
+    sec.relaxAux->relocTypes[i + 2] = R_RISCV_LO12_S;
+  }
+}
+
 // Relax local-exec TLS when hi20 is zero.
 static void relaxTlsLe(const InputSection &sec, size_t i, uint64_t loc,
                        Relocation &r, uint32_t &remove) {
@@ -701,6 +757,11 @@
           sec.relocs()[i + 1].type == R_RISCV_RELAX)
         relaxCall(sec, i, loc, r, remove);
       break;
+    case R_RISCV_PCREL_HI20:
+      if (i + 1 != sec.relocs().size() &&
+          sec.relocs()[i + 1].type == R_RISCV_RELAX)
+        relaxPcrel(sec, i, loc, r, remove);
+      break;
     case R_RISCV_TPREL_HI20:
     case R_RISCV_TPREL_ADD:
     case R_RISCV_TPREL_LO12_I:
@@ -829,6 +890,12 @@
           }
         } else if (RelType newType = aux.relocTypes[i]) {
           switch (newType) {
+          case R_RISCV_HI20:
+            skip = 4;
+            write32le(p, aux.writes[writesIdx++]);
+            break;
+          case R_RISCV_LO12_I:
+          case R_RISCV_LO12_S:
           case INTERNAL_R_RISCV_GPREL_I:
           case INTERNAL_R_RISCV_GPREL_S:
             break;
diff --git a/lld/test/ELF/riscv-relax-weak.s b/lld/test/ELF/riscv-relax-weak.s
new file mode 100644
--- /dev/null
+++ b/lld/test/ELF/riscv-relax-weak.s
@@ -0,0 +1,52 @@
+# REQUIRES: riscv
+
+## auipc -> lui relaxation
+##
+## This example uses weak undefined symbol 'foo'
+## which value would be 0 in final elf image.
+## Function '_start' that reference that symbol
+## was written/compiled with medany code model
+## in mind. That's why it uses pc-relative
+## addressing mode to access foo. However
+## if _start is put in distant address(over 2GiB from zero)
+## which is legal for medany model, foo relocation would be
+## out of range. To allow for weak references to work
+## linker should change addressing mode to absolute.
+
+# RUN: rm -rf %t && split-file %s %t && cd %t
+# RUN: llvm-mc -filetype=obj -triple=riscv64 -mattr=+relax a.s -o a.o
+# RUN: ld.lld a.o -T a.ld -o a.elf
+# RUN: llvm-objdump -d a.elf | FileCheck %s --check-prefix=RELAX
+# RUN: not ld.lld a.o -T a.ld --no-relax |& FileCheck %s --check-prefix=NOREL
+
+# RELAX: 0000001000000000 <_start>:
+# RELAX-NEXT: 1000000000: 37 05 00 00	lui	a0, 0
+# RELAX-NEXT: 1000000004: 13 05 05 00	mv	a0, a0
+
+# NOREL: relocation R_RISCV_PCREL_HI20 out of range: -16777216 is not in [-524288, 524287]; references 'foo'
+
+#--- a.s
+        .text
+        .section        .text._start,"ax",@progbits
+        .globl  _start
+        .p2align        1
+_start:
+.Lpcrel_hi0:
+        auipc   a0, %pcrel_hi(foo)
+        addi    a0, a0, %pcrel_lo(.Lpcrel_hi0)
+        beqz    a0, .LBB0_2
+        addi    sp, sp, -16
+        sd      ra, 8(sp)
+        call    foo
+        ld      ra, 8(sp)
+        addi    sp, sp, 16
+.LBB0_2:
+        ret
+        .weak   foo
+        .addrsig
+        .addrsig_sym foo
+#--- a.ld
+SECTIONS {
+  .text 0x1000000000 : { *(.text) }
+}
+