Index: lib/AST/VTableBuilder.cpp
===================================================================
--- lib/AST/VTableBuilder.cpp
+++ lib/AST/VTableBuilder.cpp
@@ -2223,6 +2223,7 @@
 ItaniumVTableContext::~ItaniumVTableContext() {}
 
 uint64_t ItaniumVTableContext::getMethodVTableIndex(GlobalDecl GD) {
+  GD = GD.getCanonicalDecl();
   MethodVTableIndicesTy::iterator I = MethodVTableIndices.find(GD);
   if (I != MethodVTableIndices.end())
     return I->second;
@@ -2503,6 +2504,8 @@
     for (const auto &I : MethodInfoMap) {
       const CXXMethodDecl *MD = I.first;
       const MethodInfo &MI = I.second;
+      assert(MD == MD->getCanonicalDecl());
+
       // Skip the methods that the MostDerivedClass didn't override
       // and the entries shadowed by return adjusting thunks.
       if (MD->getParent() != MostDerivedClass || MI.Shadowed)
@@ -3737,6 +3740,8 @@
   if (isa<CXXDestructorDecl>(GD.getDecl()))
     assert(GD.getDtorType() == Dtor_Deleting);
 
+  GD = GD.getCanonicalDecl();
+
   MethodVFTableLocationsTy::iterator I = MethodVFTableLocations.find(GD);
   if (I != MethodVFTableLocations.end())
     return I->second;
Index: lib/CodeGen/CGCXX.cpp
===================================================================
--- lib/CodeGen/CGCXX.cpp
+++ lib/CodeGen/CGCXX.cpp
@@ -267,7 +267,6 @@
                                           const CXXRecordDecl *RD) {
   assert(!CGF.CGM.getTarget().getCXXABI().isMicrosoft() &&
          "No kext in Microsoft ABI");
-  GD = GD.getCanonicalDecl();
   CodeGenModule &CGM = CGF.CGM;
   llvm::Value *VTable = CGM.getCXXABI().getAddrOfVTable(RD, CharUnits());
   Ty = Ty->getPointerTo()->getPointerTo();
@@ -283,7 +282,7 @@
     CGF.Builder.CreateConstInBoundsGEP1_64(VTable, VTableIndex, "vfnkxt");
   llvm::Value *VFunc =
     CGF.Builder.CreateAlignedLoad(VFuncPtr, CGF.PointerAlignInBytes);
-  CGCallee Callee(GD.getDecl(), VFunc);
+  CGCallee Callee(GD.getDecl()->getCanonicalDecl(), VFunc);
   return Callee;
 }
 
Index: lib/CodeGen/ItaniumCXXABI.cpp
===================================================================
--- lib/CodeGen/ItaniumCXXABI.cpp
+++ lib/CodeGen/ItaniumCXXABI.cpp
@@ -825,7 +825,6 @@
 llvm::Constant *ItaniumCXXABI::BuildMemberPointer(const CXXMethodDecl *MD,
                                                   CharUnits ThisAdjustment) {
   assert(MD->isInstance() && "Member function must not be static!");
-  MD = MD->getCanonicalDecl();
 
   CodeGenTypes &Types = CGM.getTypes();
 
@@ -1640,7 +1639,6 @@
                                                   Address This,
                                                   llvm::Type *Ty,
                                                   SourceLocation Loc) {
-  GD = GD.getCanonicalDecl();
   Ty = Ty->getPointerTo()->getPointerTo();
   auto *MethodDecl = cast<CXXMethodDecl>(GD.getDecl());
   llvm::Value *VTable = CGF.GetVTablePtr(This, Ty, MethodDecl->getParent());
@@ -1674,7 +1672,7 @@
     VFunc = VFuncLoad;
   }
 
-  CGCallee Callee(MethodDecl, VFunc);
+  CGCallee Callee(MethodDecl->getCanonicalDecl(), VFunc);
   return Callee;
 }
 
Index: lib/CodeGen/MicrosoftCXXABI.cpp
===================================================================
--- lib/CodeGen/MicrosoftCXXABI.cpp
+++ lib/CodeGen/MicrosoftCXXABI.cpp
@@ -228,7 +228,6 @@
 
   const CXXRecordDecl *
   getThisArgumentTypeForMethod(const CXXMethodDecl *MD) override {
-    MD = MD->getCanonicalDecl();
     if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD)) {
       MethodVFTableLocation ML =
           CGM.getMicrosoftVTableContext().getMethodVFTableLocation(MD);
@@ -1320,10 +1319,8 @@
 
 CharUnits
 MicrosoftCXXABI::getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) {
-  GD = GD.getCanonicalDecl();
   const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
 
-  GlobalDecl LookupGD = GD;
   if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
     // Complete destructors take a pointer to the complete object as a
     // parameter, thus don't need this adjustment.
@@ -1332,11 +1329,11 @@
 
     // There's no Dtor_Base in vftable but it shares the this adjustment with
     // the deleting one, so look it up instead.
-    LookupGD = GlobalDecl(DD, Dtor_Deleting);
+    GD = GlobalDecl(DD, Dtor_Deleting);
   }
 
   MethodVFTableLocation ML =
-      CGM.getMicrosoftVTableContext().getMethodVFTableLocation(LookupGD);
+      CGM.getMicrosoftVTableContext().getMethodVFTableLocation(GD);
   CharUnits Adjustment = ML.VFPtrOffset;
 
   // Normal virtual instance methods need to adjust from the vfptr that first
@@ -1370,7 +1367,6 @@
     return CGF.Builder.CreateConstByteGEP(This, Adjustment);
   }
 
-  GD = GD.getCanonicalDecl();
   const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
 
   GlobalDecl LookupGD = GD;
@@ -1839,7 +1835,6 @@
                                                     Address This,
                                                     llvm::Type *Ty,
                                                     SourceLocation Loc) {
-  GD = GD.getCanonicalDecl();
   CGBuilderTy &Builder = CGF.Builder;
 
   Ty = Ty->getPointerTo()->getPointerTo();
@@ -1878,7 +1873,7 @@
     VFunc = Builder.CreateAlignedLoad(VFuncPtr, CGF.getPointerAlign());
   }
 
-  CGCallee Callee(MethodDecl, VFunc);
+  CGCallee Callee(MethodDecl->getCanonicalDecl(), VFunc);
   return Callee;
 }
 
@@ -2737,7 +2732,6 @@
 MicrosoftCXXABI::EmitMemberFunctionPointer(const CXXMethodDecl *MD) {
   assert(MD->isInstance() && "Member function must not be static!");
 
-  MD = MD->getCanonicalDecl();
   CharUnits NonVirtualBaseAdjustment = CharUnits::Zero();
   const CXXRecordDecl *RD = MD->getParent()->getMostRecentDecl();
   CodeGenTypes &Types = CGM.getTypes();
@@ -2760,7 +2754,7 @@
   } else {
     auto &VTableContext = CGM.getMicrosoftVTableContext();
     MethodVFTableLocation ML = VTableContext.getMethodVFTableLocation(MD);
-    FirstField = EmitVirtualMemPtrThunk(MD, ML);
+    FirstField = EmitVirtualMemPtrThunk(MD->getCanonicalDecl(), ML);
     // Include the vfptr adjustment if the method is in a non-primary vftable.
     NonVirtualBaseAdjustment += ML.VFPtrOffset;
     if (ML.VBase)
Index: test/CodeGenCXX/PR37481.cpp
===================================================================
--- /dev/null
+++ test/CodeGenCXX/PR37481.cpp
@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -o /dev/null -emit-llvm -std=c++17 -triple x86_64-pc-windows-msvc %s
+
+struct Foo {
+  virtual void f();
+  virtual void g();
+};
+
+void Foo::f() {}
+void Foo::g() {}
+
+template <void (Foo::*)()>
+void h() {}
+
+void x() {
+  h<&Foo::f>();
+  h<&Foo::g>();
+}