diff --git a/lld/MachO/ConcatOutputSection.cpp b/lld/MachO/ConcatOutputSection.cpp
index 99e4558ab82f..87a6b3f18f48 100644
--- a/lld/MachO/ConcatOutputSection.cpp
+++ b/lld/MachO/ConcatOutputSection.cpp
@@ -241,6 +241,8 @@ void ConcatOutputSection::finalize() {
     }
     // Process relocs by ascending address, i.e., ascending offset within isec
     std::vector<Reloc> &relocs = isec->relocs;
+    // FIXME: This property does not hold for object files produced by ld64's
+    // `-r` mode.
     assert(is_sorted(relocs,
                      [](Reloc &a, Reloc &b) { return a.offset > b.offset; }));
     for (Reloc &r : reverse(relocs)) {
diff --git a/lld/MachO/InputFiles.cpp b/lld/MachO/InputFiles.cpp
index fd42f57ad378..703050157328 100644
--- a/lld/MachO/InputFiles.cpp
+++ b/lld/MachO/InputFiles.cpp
@@ -366,6 +366,7 @@ void ObjFile::parseRelocations(ArrayRef<Section> sectionHeaders,
   ArrayRef<relocation_info> relInfos(
       reinterpret_cast<const relocation_info *>(buf + sec.reloff), sec.nreloc);
 
+  auto subsecIt = subsecMap.rbegin();
   for (size_t i = 0; i < relInfos.size(); i++) {
     // Paired relocations serve as Mach-O's method for attaching a
     // supplemental datum to a primary relocation record. ELF does not
@@ -440,7 +441,24 @@ void ObjFile::parseRelocations(ArrayRef<Section> sectionHeaders,
       r.addend = referentOffset;
     }
 
-    InputSection *subsec = findContainingSubsection(subsecMap, &r.offset);
+    // Find the subsection that this relocation belongs to.
+    // Though not required by the Mach-O format, clang and gcc seem to emit
+    // relocations in order, so let's take advantage of it. However, ld64 emits
+    // unsorted relocations (in `-r` mode), so we have a fallback for that
+    // uncommon case.
+    InputSection *subsec;
+    while (subsecIt != subsecMap.rend() && subsecIt->offset > r.offset)
+      ++subsecIt;
+    if (subsecIt == subsecMap.rend() ||
+        subsecIt->offset + subsecIt->isec->getSize() <= r.offset) {
+      subsec = findContainingSubsection(subsecMap, &r.offset);
+      // Now that we know the relocs are unsorted, avoid trying the 'fast path'
+      // for the other relocations.
+      subsecIt = subsecMap.rend();
+    } else {
+      subsec = subsecIt->isec;
+      r.offset -= subsecIt->offset;
+    }
     subsec->relocs.push_back(r);
 
     if (isSubtrahend) {
diff --git a/lld/test/MachO/unsorted-relocations.yaml b/lld/test/MachO/unsorted-relocations.yaml
new file mode 100644
index 000000000000..c33b779050a7
--- /dev/null
+++ b/lld/test/MachO/unsorted-relocations.yaml
@@ -0,0 +1,106 @@
+## This tests that we can handle relocations that are not sorted by address.
+## llvm-mc isn't able to emit such a file, hence the use of yaml2obj. ld64
+## may emit files with unsorted relocations in `-r` mode, so we need to support
+## this.
+
+# RUN: yaml2obj %s -o %t.o
+# RUN: %lld -dylib -o %t %t.o
+# RUN: llvm-objdump --macho -d %t | FileCheck %s
+
+# CHECK:      _foo:
+# CHECK-NEXT:      movq    _bar(%rip), %rax
+# CHECK-NEXT: _bar:
+# CHECK-NEXT:      movq    _baz(%rip), %rax
+# CHECK-NEXT: _baz:
+# CHECK-NEXT:      movq    _foo(%rip), %rax
+
+--- !mach-o
+FileHeader:
+  magic:           0xFEEDFACF
+  cputype:         0x1000007
+  cpusubtype:      0x3
+  filetype:        0x1
+  ncmds:           2
+  sizeofcmds:      280
+  flags:           0x2000
+  reserved:        0x0
+LoadCommands:
+  - cmd:             LC_SEGMENT_64
+    cmdsize:         152
+    segname:         ''
+    vmaddr:          0
+    vmsize:          21
+    fileoff:         312
+    filesize:        21
+    maxprot:         7
+    initprot:        7
+    nsects:          1
+    flags:           0
+    Sections:
+      - sectname:        __text
+        segname:         __TEXT
+        addr:            0x0
+        size:            21
+        offset:          0x138
+        align:           0
+        reloff:          0x150
+        nreloc:          3
+        flags:           0x80000400
+        reserved1:       0x0
+        reserved2:       0x0
+        reserved3:       0x0
+        content:         488B0500000000488B0500000000488B0500000000
+        relocations:
+          - address:         0x3
+            symbolnum:       1
+            pcrel:           true
+            length:          2
+            extern:          true
+            type:            1
+            scattered:       false
+            value:           0
+          - address:         0x11
+            symbolnum:       0
+            pcrel:           true
+            length:          2
+            extern:          true
+            type:            1
+            scattered:       false
+            value:           0
+          - address:         0xA
+            symbolnum:       2
+            pcrel:           true
+            length:          2
+            extern:          true
+            type:            1
+            scattered:       false
+            value:           0
+  - cmd:             LC_SYMTAB
+    cmdsize:         24
+    symoff:          360
+    nsyms:           3
+    stroff:          408
+    strsize:         16
+LinkEditData:
+  NameList:
+    - n_strx:          11
+      n_type:          0xE
+      n_sect:          1
+      n_desc:          0
+      n_value:         0
+    - n_strx:          6
+      n_type:          0xE
+      n_sect:          1
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+    - n_strx:          1
+      n_type:          0xE
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+  StringTable:
+    - ''
+    - _baz
+    - _bar
+    - _foo
+...