diff --git a/llvm/test/tools/llvm-nm/XCOFF/demangle.test b/llvm/test/tools/llvm-nm/XCOFF/demangle.test
new file mode 100644
--- /dev/null
+++ b/llvm/test/tools/llvm-nm/XCOFF/demangle.test
@@ -0,0 +1,31 @@
+## Test llvm-nm demangling of symbols for XCOFF object files.
+# RUN: llvm-nm  --demangle %p/Inputs/test_xlclang.o | FileCheck --check-prefix=NM-DEMANGLE %s
+
+## test_xlclang.o is generated by the following source compiled with IBM xlclang++ in aix os.
+## int value = 0;
+##
+## __attribute__ ((weak))  int weak_value = 5;
+##
+## static int func0 () {
+##   return value;
+## }
+##
+## int func1 (int i) {
+##   return func0() * i;
+## }
+
+# NM-DEMANGLE:      00000000 t
+# NM-DEMANGLE-NEXT: 00000040 T .func1(int)
+# NM-DEMANGLE-NEXT: 00000000 t .func0()
+# NM-DEMANGLE-NEXT: 00000120 b .bss
+# NM-DEMANGLE-NEXT: 00000100 d .data
+# NM-DEMANGLE-NEXT: 00000000 f .file
+# NM-DEMANGLE-NEXT: 00000000 t .text
+# NM-DEMANGLE-NEXT: 00000100 d TOC
+# NM-DEMANGLE-NEXT: 00000104 d func1(int)
+# NM-DEMANGLE-NEXT: 0000010c D func1(int)
+# NM-DEMANGLE-NEXT: 00000100 d value
+# NM-DEMANGLE-NEXT: 00000118 D value
+# NM-DEMANGLE-NEXT: 00000108 d weak_value
+# NM-DEMANGLE-NEXT: 0000011c W weak_value
+~
diff --git a/llvm/tools/llvm-nm/llvm-nm.cpp b/llvm/tools/llvm-nm/llvm-nm.cpp
--- a/llvm/tools/llvm-nm/llvm-nm.cpp
+++ b/llvm/tools/llvm-nm/llvm-nm.cpp
@@ -619,10 +619,7 @@
     outs() << format("   %02x", NType);
 }
 
-static Optional<std::string> demangle(StringRef Name, bool StripUnderscore) {
-  if (StripUnderscore && !Name.empty() && Name[0] == '_')
-    Name = Name.substr(1);
-
+static Optional<std::string> demangle(StringRef Name) {
   if (!Name.startswith("_Z"))
     return None;
 
@@ -637,6 +634,24 @@
   return S;
 }
 
+static Optional<std::string> demangleXCOFF(StringRef Name) {
+  if (!Name.empty() && Name[0] == '.')
+    Name = Name.substr(1);
+  else
+    return demangle(Name);
+
+  Optional<std::string> DemangledName = demangle(Name);
+  if (DemangledName)
+    return "." + *DemangledName;
+  return None;
+}
+
+static Optional<std::string> demangleMachO(StringRef Name) {
+  if (!Name.empty() && Name[0] == '_')
+    Name = Name.substr(1);
+  return demangle(Name);
+}
+
 static bool symbolIsDefined(const NMSymbol &Sym) {
   return Sym.TypeChar != 'U' && Sym.TypeChar != 'w' && Sym.TypeChar != 'v';
 }
@@ -725,7 +740,12 @@
     std::string Name = S.Name;
     MachOObjectFile *MachO = dyn_cast<MachOObjectFile>(&Obj);
     if (Demangle) {
-      if (Optional<std::string> Opt = demangle(S.Name, MachO))
+      function_ref<Optional<std::string>(StringRef)> Fn = ::demangle;
+      if (Obj.isXCOFF())
+        Fn = demangleXCOFF;
+      if (Obj.isMachO())
+        Fn = demangleMachO;
+      if (Optional<std::string> Opt = Fn(S.Name))
         Name = *Opt;
     }
     if (S.Sym.getRawDataRefImpl().p) {