diff --git a/clang/test/CodeGen/thinlto-distributed-cfi-devirt.ll b/clang/test/CodeGen/thinlto-distributed-cfi-devirt.ll
--- a/clang/test/CodeGen/thinlto-distributed-cfi-devirt.ll
+++ b/clang/test/CodeGen/thinlto-distributed-cfi-devirt.ll
@@ -85,8 +85,8 @@
   %4 = bitcast i8* %3 to i32 (%struct.A*, i32)*
 
   ; Check that the call was devirtualized.
-  ; CHECK-IR: %call = tail call i32 @_ZN1A1nEi
-  ; SKIP-IR-NOT: %call = tail call i32 @_ZN1A1nEi
+  ; CHECK-IR: %call = tail call i32 bitcast (void ()* @_ZN1A1nEi
+  ; SKIP-IR-NOT: %call = tail call i32 {{.*}}@_ZN1A1nEi
   %call = tail call i32 %4(%struct.A* nonnull %obj, i32 %a)
   %vtable16 = load i8*, i8** %0
   %5 = tail call { i8*, i1 } @llvm.type.checked.load(i8* %vtable16, i32 0, metadata !"_ZTS1A")
diff --git a/llvm/lib/LTO/LTOBackend.cpp b/llvm/lib/LTO/LTOBackend.cpp
--- a/llvm/lib/LTO/LTOBackend.cpp
+++ b/llvm/lib/LTO/LTOBackend.cpp
@@ -543,20 +543,30 @@
 
 static void dropDeadSymbols(Module &Mod, const GVSummaryMapTy &DefinedGlobals,
                             const ModuleSummaryIndex &Index) {
-  std::vector<GlobalValue*> DeadGVs;
-  for (auto &GV : Mod.global_values())
-    if (GlobalValueSummary *GVS = DefinedGlobals.lookup(GV.getGUID()))
+  std::vector<GlobalValue *> Declarations;
+  for (auto &GV : Mod.global_values()) {
+    if (GlobalValueSummary *GVS = DefinedGlobals.lookup(GV.getGUID())) {
       if (!Index.isGlobalValueLive(GVS)) {
-        DeadGVs.push_back(&GV);
+        Declarations.push_back(&GV);
         convertToDeclaration(GV);
       }
+    } else if (GV.isDeclaration())
+      // Check if any pre-existing declarations are unused after dead
+      // definitions are removed.
+      Declarations.push_back(&GV);
+  }
 
-  // Now that all dead bodies have been dropped, delete the actual objects
-  // themselves when possible.
-  for (GlobalValue *GV : DeadGVs) {
+  // Now that all dead bodies have been dropped, delete the declarations
+  // themselves when possible. Note this is important to avoid introducing
+  // calls to these functions during indirect call promotion, e.g. when using a
+  // sample profile from a different binary or different version of the source,
+  // that may reference virtual functions not live in this binary.
+  for (GlobalValue *GV : Declarations) {
     GV->removeDeadConstantUsers();
-    // Might reference something defined in native object (i.e. dropped a
-    // non-prevailing IR def, but we need to keep the declaration).
+    // Might have a reference to something defined in native object
+    // (i.e. dropped a non-prevailing IR def), so we need to keep the
+    // declaration. In this case there is a definition somewhere, so
+    // keeping the declaration should not cause any issues.
     if (GV->use_empty())
       GV->eraseFromParent();
   }
diff --git a/llvm/test/LTO/Resolution/X86/load-sample-prof-icp.ll b/llvm/test/LTO/Resolution/X86/load-sample-prof-icp.ll
--- a/llvm/test/LTO/Resolution/X86/load-sample-prof-icp.ll
+++ b/llvm/test/LTO/Resolution/X86/load-sample-prof-icp.ll
@@ -23,6 +23,11 @@
   %3 = load void ()*, void ()** %2
   ; CHECK: call void @bar(),{{.*}}!prof
   call void %3(), !dbg !10
+  ; Call bar directly so we don't eliminate the unused declaration before ICP,
+  ; which will block it.
+  ; CHECK: if.end.icp:
+  ; CHECK-NEXT: call void @bar()
+  call void @bar()
   ret void
 }
 
diff --git a/llvm/test/ThinLTO/X86/cfi-devirt.ll b/llvm/test/ThinLTO/X86/cfi-devirt.ll
--- a/llvm/test/ThinLTO/X86/cfi-devirt.ll
+++ b/llvm/test/ThinLTO/X86/cfi-devirt.ll
@@ -97,7 +97,7 @@
   %4 = bitcast i8* %3 to i32 (%struct.A*, i32)*
 
   ; Check that the call was devirtualized.
-  ; CHECK-IR: %call = tail call i32 @_ZN1A1nEi
+  ; CHECK-IR: %call = tail call i32 bitcast (void ()* @_ZN1A1nEi
   %call = tail call i32 %4(%struct.A* nonnull %obj, i32 %a)
   %vtable16 = load i8*, i8** %0
   %5 = tail call { i8*, i1 } @llvm.type.checked.load(i8* %vtable16, i32 0, metadata !"_ZTS1A")
diff --git a/llvm/test/ThinLTO/X86/devirt-after-icp.ll b/llvm/test/ThinLTO/X86/devirt-after-icp.ll
--- a/llvm/test/ThinLTO/X86/devirt-after-icp.ll
+++ b/llvm/test/ThinLTO/X86/devirt-after-icp.ll
@@ -120,7 +120,7 @@
   %8 = load i32 (%class.B*)*, i32 (%class.B*)** %vfn.i, align 8
 ; Call to bar() can be devirtualized to call to B::bar(), since it was
 ; inlined from B::foo() after ICP introduced the guarded promotion.
-; CHECK-IR: %call.i = tail call i32 @_ZN1B3barEv(%class.B* %3)
+; CHECK-IR: %call.i = tail call i32 bitcast (void ()* @_ZN1B3barEv to i32 (%class.B*)*)(%class.B* %3)
   %call.i = tail call i32 %8(%class.B* %5)
   br label %if.end.icp
 
diff --git a/llvm/test/ThinLTO/X86/index-const-prop-alias.ll b/llvm/test/ThinLTO/X86/index-const-prop-alias.ll
--- a/llvm/test/ThinLTO/X86/index-const-prop-alias.ll
+++ b/llvm/test/ThinLTO/X86/index-const-prop-alias.ll
@@ -15,16 +15,13 @@
 ; RUN:               %t2.bc -r=%t2.bc,g,pl -r=%t2.bc,g.alias,plx -save-temps -o %t5
 ; RUN: llvm-dis %t5.1.3.import.bc -o - | FileCheck %s --check-prefix=PRESERVED
 
-; We currently don't support importing aliases
-; IMPORT:       @g.alias = external global i32
-; IMPORT-NEXT:  @g = internal global i32 42, align 4 #0
+; IMPORT:  @g = internal global i32 42, align 4 #0
 ; IMPORT:  attributes #0 = { "thinlto-internalize" }
 
 ; CODEGEN:      define dso_local i32 @main
 ; CODEGEN-NEXT:    ret i32 42
 
-; PRESERVED:      @g.alias = external global i32
-; PRESERVED-NEXT: @g = available_externally global i32 42, align 4
+; PRESERVED: @g = available_externally global i32 42, align 4
 
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/ThinLTO/X86/index-const-prop-dead.ll b/llvm/test/ThinLTO/X86/index-const-prop-dead.ll
--- a/llvm/test/ThinLTO/X86/index-const-prop-dead.ll
+++ b/llvm/test/ThinLTO/X86/index-const-prop-dead.ll
@@ -4,9 +4,9 @@
 ; RUN:               %t1.bc -r=%t1.bc,main,plx -r=%t1.bc,foo,pl -r=%t1.bc,g, -o %t3
 ; RUN: llvm-dis %t3.2.3.import.bc -o - | FileCheck %s
 
-; Dead globals are converted to declarations by ThinLTO in dropDeadSymbols
-; If we try to internalize such we'll get a broken module. 
-; CHECK: @g = external global i32
+; Dead globals are converted to declarations by ThinLTO, and unused declarations
+; are removed, in dropDeadSymbols,
+; CHECK-NOT: @g
 
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"