diff --git a/llvm/test/tools/llvm-objcopy/MachO/install-name-tool-add-rpath.test b/llvm/test/tools/llvm-objcopy/MachO/install-name-tool-add-rpath.test
--- a/llvm/test/tools/llvm-objcopy/MachO/install-name-tool-add-rpath.test
+++ b/llvm/test/tools/llvm-objcopy/MachO/install-name-tool-add-rpath.test
@@ -22,6 +22,13 @@
 
 # NO-INPUT: no input file specified
 
+## Add same RPATH twice:
+# RUN: not llvm-install-name-tool -add_rpath @executable_X \
+# RUN:                            -add_rpath @executable_X %t.i386 2>&1 \
+# RUN: | FileCheck --check-prefix=DOUBLE %s
+
+# DOUBLE: duplicate load command
+
 ## Check that cmdsize accounts for NULL terminator.
 # RUN: yaml2obj %p/Inputs/x86_64.yaml -o %t.x86_64
 # RUN: llvm-install-name-tool -add_rpath abcd %t.x86_64
diff --git a/llvm/tools/llvm-objcopy/MachO/MachOObjcopy.cpp b/llvm/tools/llvm-objcopy/MachO/MachOObjcopy.cpp
--- a/llvm/tools/llvm-objcopy/MachO/MachOObjcopy.cpp
+++ b/llvm/tools/llvm-objcopy/MachO/MachOObjcopy.cpp
@@ -155,6 +155,76 @@
   return LC;
 }
 
+static Error updateLoadCommands(const CopyConfig &Config, Object &Obj) {
+  DenseSet<StringRef> OriginalRPaths;
+  auto FindPair =
+      [](StringRef Old,
+         const std::vector<std::pair<StringRef, StringRef>> &Range) {
+        return find_if(Range, [=](const std::pair<StringRef, StringRef> Pair) {
+          return Pair.first == Old;
+        });
+      };
+
+  for (LoadCommand &LC : Obj.LoadCommands) {
+    switch (LC.MachOLoadCommand.load_command_data.cmd) {
+    case MachO::LC_ID_DYLIB:
+      if (Config.SharedLibId) {
+        StringRef Id = Config.SharedLibId.getValue();
+        if (Id.empty())
+          return createStringError(errc::invalid_argument,
+                                   "cannot specify an empty id");
+        updateLoadCommandPayloadString<MachO::dylib_command>(LC, Id);
+      }
+      break;
+
+    case MachO::LC_RPATH: {
+      StringRef CurrentRPath = getPayloadString(LC);
+      auto FoundArg = FindPair(CurrentRPath, Config.RPathsToUpdate);
+      if (FoundArg != Config.RPathsToUpdate.end()) {
+        updateLoadCommandPayloadString<MachO::rpath_command>(LC,
+                                                             FoundArg->second);
+        OriginalRPaths.insert(FoundArg->first);
+      } else {
+        OriginalRPaths.insert(CurrentRPath);
+      }
+      break;
+    }
+
+    case MachO::LC_LOAD_DYLIB:
+    case MachO::LC_LOAD_WEAK_DYLIB:
+      StringRef CurrentInstallName = getPayloadString(LC);
+      auto FoundArg = FindPair(CurrentInstallName, Config.InstallNamesToUpdate);
+      if (FoundArg != Config.InstallNamesToUpdate.end())
+        updateLoadCommandPayloadString<MachO::dylib_command>(LC,
+                                                             FoundArg->second);
+      break;
+    }
+  }
+
+  StringRef Old, New;
+  for (const auto &OldNew : Config.RPathsToUpdate) {
+    std::tie(Old, New) = OldNew;
+    if (OriginalRPaths.count(Old) == 0)
+      return createStringError(errc::invalid_argument,
+                               "no LC_RPATH load command with path: " + Old);
+    if (OriginalRPaths.count(New) != 0)
+      return createStringError(errc::invalid_argument,
+                               "rpath " + New +
+                                   " would create a duplicate load command");
+  }
+
+  for (StringRef RPath : Config.RPathToAdd) {
+    if (OriginalRPaths.count(RPath) != 0)
+      return createStringError(errc::invalid_argument,
+                               "rpath " + RPath +
+                                   " would create a duplicate load command");
+    OriginalRPaths.insert(RPath);
+    Obj.addLoadCommand(buildRPathLoadCommand(RPath));
+  }
+
+  return Error::success();
+}
+
 static Error dumpSectionToFile(StringRef SecName, StringRef Filename,
                                Object &Obj) {
   for (LoadCommand &LC : Obj.LoadCommands)
@@ -271,32 +341,6 @@
       for (std::unique_ptr<Section> &Sec : LC.Sections)
         Sec->Relocations.clear();
 
-  for (LoadCommand &LC : Obj.LoadCommands) {
-    switch (LC.MachOLoadCommand.load_command_data.cmd) {
-    case MachO::LC_ID_DYLIB:
-      if (Config.SharedLibId) {
-        StringRef Id = Config.SharedLibId.getValue();
-        if (Id.empty())
-          return createStringError(errc::invalid_argument,
-                                   "cannot specify an empty id");
-        updateLoadCommandPayloadString<MachO::dylib_command>(LC, Id);
-      }
-      break;
-
-    case MachO::LC_LOAD_DYLIB:
-    case MachO::LC_LOAD_WEAK_DYLIB:
-      StringRef Old, New;
-      StringRef CurrentInstallName = getPayloadString(LC);
-      for (const auto &InstallNamePair : Config.InstallNamesToUpdate) {
-        std::tie(Old, New) = InstallNamePair;
-        if (CurrentInstallName == Old) {
-          updateLoadCommandPayloadString<MachO::dylib_command>(LC, New);
-          break;
-        }
-      }
-    }
-  }
-
   for (const auto &Flag : Config.AddSection) {
     std::pair<StringRef, StringRef> SecPair = Flag.split("=");
     StringRef SecName = SecPair.first;
@@ -310,42 +354,9 @@
   if (Error E = removeLoadCommands(Config, Obj))
     return E;
 
-  StringRef Old, New;
-  for (const auto &OldNew : Config.RPathsToUpdate) {
-    std::tie(Old, New) = OldNew;
-
-    auto FindRPathLC = [&Obj](StringRef RPath) {
-      return find_if(Obj.LoadCommands, [=](const LoadCommand &LC) {
-        return LC.MachOLoadCommand.load_command_data.cmd == MachO::LC_RPATH &&
-               getPayloadString(LC) == RPath;
-      });
-    };
-
-    auto NewIt = FindRPathLC(New);
-    if (NewIt != Obj.LoadCommands.end())
-      return createStringError(errc::invalid_argument,
-                               "rpath " + New +
-                                   " would create a duplicate load command");
-
-    auto OldIt = FindRPathLC(Old);
-    if (OldIt == Obj.LoadCommands.end())
-      return createStringError(errc::invalid_argument,
-                               "no LC_RPATH load command with path: " + Old);
-
-    updateLoadCommandPayloadString<MachO::rpath_command>(*OldIt, New);
-  }
+  if (Error E = updateLoadCommands(Config, Obj))
+    return E;
 
-  for (StringRef RPath : Config.RPathToAdd) {
-    for (LoadCommand &LC : Obj.LoadCommands) {
-      if (LC.MachOLoadCommand.load_command_data.cmd == MachO::LC_RPATH &&
-          RPath == getPayloadString(LC)) {
-        return createStringError(errc::invalid_argument,
-                                 "rpath " + RPath +
-                                     " would create a duplicate load command");
-      }
-    }
-    Obj.addLoadCommand(buildRPathLoadCommand(RPath));
-  }
   return Error::success();
 }