Index: lld/ELF/Driver.cpp
===================================================================
--- lld/ELF/Driver.cpp
+++ lld/ELF/Driver.cpp
@@ -47,6 +47,7 @@
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/ADT/UniqueVector.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/LTO/LTO.h"
 #include "llvm/Object/Archive.h"
@@ -594,7 +595,10 @@
 
 static std::string getRpath(opt::InputArgList &args) {
   std::vector<StringRef> v = args::getStrings(args, OPT_rpath);
-  return llvm::join(v.begin(), v.end(), ":");
+  llvm::UniqueVector<StringRef> u;
+  for (StringRef p : v)
+      u.insert(p);
+  return llvm::join(u.begin(), u.end(), ":");
 }
 
 // Determines what we should do if there are remaining unresolved
Index: lld/docs/ReleaseNotes.rst
===================================================================
--- lld/docs/ReleaseNotes.rst
+++ lld/docs/ReleaseNotes.rst
@@ -31,6 +31,9 @@
 * ``--no-fortran-common`` (pre 12.0.0 behavior) is now the default.
 * ``FORCE_LLD_DIAGNOSTICS_CRASH`` environment variable is now available to force LLD to crash.
   (`D128195 <https://reviews.llvm.org/D128195>`_)
+* Duplicate ``-rpath`` arguments with an identical path are ignored now, matching GNU ld and gold
+  behavior.
+  (`D129142 <https://reviews.llvm.org/D129142>`_)
 
 Breaking changes
 ----------------
Index: lld/test/ELF/duplicated-rpath.test
===================================================================
--- /dev/null
+++ lld/test/ELF/duplicated-rpath.test
@@ -0,0 +1,12 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
+
+## Duplicated /path1 and /path2 shall only appear once each:
+# RUN: ld.lld %t.o -rpath=/path1 -rpath=/path12 -rpath=/path2 -rpath=/path2 -rpath=/path1 -shared -o %t
+# RUN: llvm-readobj --dynamic-table %t | FileCheck %s
+# CHECK: Library runpath: [/path1:/path12:/path2]
+
+## Degenerate case where an -rpath argument already contains a colon:
+# RUN: ld.lld %t.o -rpath=/path1 -rpath=/path1:/path2 -rpath=/path2 -shared -o %t
+# RUN: llvm-readobj --dynamic-table %t | FileCheck --check-prefix=DEGENERATE %s
+# DEGENERATE: Library runpath: [/path1:/path1:/path2:/path2]