diff --git a/llvm/lib/DebugInfo/Symbolize/Symbolize.cpp b/llvm/lib/DebugInfo/Symbolize/Symbolize.cpp
--- a/llvm/lib/DebugInfo/Symbolize/Symbolize.cpp
+++ b/llvm/lib/DebugInfo/Symbolize/Symbolize.cpp
@@ -649,22 +649,29 @@
 // vectorcall  - foo@@12
 // These are all different linkage names for 'foo'.
 StringRef demanglePE32ExternCFunc(StringRef SymbolName) {
-  // Remove any '_' or '@' prefix.
   char Front = SymbolName.empty() ? '\0' : SymbolName[0];
-  if (Front == '_' || Front == '@')
-    SymbolName = SymbolName.drop_front();
 
   // Remove any '@[0-9]+' suffix.
+  bool HasAtNumSuffix = false;
   if (Front != '?') {
     size_t AtPos = SymbolName.rfind('@');
     if (AtPos != StringRef::npos &&
-        all_of(drop_begin(SymbolName, AtPos + 1), isDigit))
+        all_of(drop_begin(SymbolName, AtPos + 1), isDigit)) {
       SymbolName = SymbolName.substr(0, AtPos);
+      HasAtNumSuffix = true;
+    }
   }
 
   // Remove any ending '@' for vectorcall.
-  if (SymbolName.endswith("@"))
+  bool IsVectorCall = false;
+  if (HasAtNumSuffix && SymbolName.endswith("@")) {
     SymbolName = SymbolName.drop_back();
+    IsVectorCall = true;
+  }
+
+  // If not vectorcall, remove any '_' or '@' prefix.
+  if (!IsVectorCall && (Front == '_' || Front == '@'))
+    SymbolName = SymbolName.drop_front();
 
   return SymbolName;
 }
@@ -692,8 +699,14 @@
     return Result;
   }
 
-  if (DbiModuleDescriptor && DbiModuleDescriptor->isWin32Module())
-    return std::string(demanglePE32ExternCFunc(Name));
+  if (DbiModuleDescriptor && DbiModuleDescriptor->isWin32Module()) {
+    std::string DemangledCName(demanglePE32ExternCFunc(Name));
+    // On i386 Windows, the C name mangling for different calling conventions
+    // may also be applied on top of the Itanium or Rust name mangling.
+    if (nonMicrosoftDemangle(DemangledCName.c_str(), Result))
+      return Result;
+    return DemangledCName;
+  }
   return Name;
 }
 
diff --git a/llvm/test/DebugInfo/symbolize-demangling-mingw32.s b/llvm/test/DebugInfo/symbolize-demangling-mingw32.s
new file mode 100644
--- /dev/null
+++ b/llvm/test/DebugInfo/symbolize-demangling-mingw32.s
@@ -0,0 +1,80 @@
+# REQUIRES: x86-registered-target
+
+# RUN: llvm-mc --filetype=obj --triple=i386-w64-windows-gnu %s -o %t.o -g
+
+# RUN: llvm-symbolizer --obj=%t.o 0 1 2 3 4 5 6 | FileCheck %s
+
+  .def g
+  .scl 2
+  .type 32
+  .endef
+g:
+  nop
+# CHECK:       {{^g$}}
+# CHECK-NEXT:  symbolize-demangling-mingw32.s:12
+# CHECK-EMPTY:
+
+  .def baz
+  .scl 2
+  .type 32
+  .endef
+baz:
+  nop
+# CHECK-NEXT:  {{^baz$}}
+# CHECK-NEXT:  symbolize-demangling-mingw32.s:22
+# CHECK-EMPTY:
+
+# void f() {} // __cdecl
+  .def __Z1fv
+  .scl 2
+  .type 32
+  .endef
+__Z1fv:
+  nop
+# CHECK-NEXT:  {{^f\(\)$}}
+# CHECK-NEXT:  symbolize-demangling-mingw32.s:33
+# CHECK-EMPTY:
+
+# void __stdcall f1() {}
+  .def __Z2f1v@0
+  .scl 2
+  .type 32
+  .endef
+__Z2f1v@0:
+  nop
+# CHECK-NEXT:  {{^f1\(\)$}}
+# CHECK-NEXT:  symbolize-demangling-mingw32.s:44
+# CHECK-EMPTY:
+
+# void __fastcall f2(void) {}
+  .def @_Z2f2v@0
+  .scl 2
+  .type 32
+  .endef
+@_Z2f2v@0:
+  nop
+# CHECK-NEXT:  {{^f2\(\)$}}
+# CHECK-NEXT:  symbolize-demangling-mingw32.s:55
+# CHECK-EMPTY:
+
+# void __vectorcall f3(void) {}
+  .def _Z2f3v@@0
+  .scl 2
+  .type 32
+  .endef
+_Z2f3v@@0:
+  nop
+# CHECK-NEXT:  {{^f3\(\)$}}
+# CHECK-NEXT:  symbolize-demangling-mingw32.s:66
+# CHECK-EMPTY:
+
+# Rust
+  .def __RNvC1x1y
+  .scl 2
+  .type 32
+  .endef
+__RNvC1x1y:
+  nop
+# CHECK-NEXT:  {{^x::y$}}
+# CHECK-NEXT:  symbolize-demangling-mingw32.s:77
+# CHECK-EMPTY: