Index: lib/CodeGen/CodeGenFunction.cpp
===================================================================
--- lib/CodeGen/CodeGenFunction.cpp
+++ lib/CodeGen/CodeGenFunction.cpp
@@ -782,6 +782,21 @@
     }
   }
 
+  // Ignore unrelated casts from C++ calls to allocate(). Don't match on the
+  // namespace because not all allocators are in std::
+  if (D && SanOpts.has(SanitizerKind::CFIUnrelatedCast)) {
+    auto *MD = dyn_cast_or_null<CXXMethodDecl>(D);
+    if (MD && MD->getName().equals("allocate") && MD->getNumParams() == 2) {
+      auto *BT = MD->parameters()[0]->getType()->getAs<BuiltinType>();
+      auto *PT = MD->parameters()[1]->getType()->getAs<PointerType>();
+      if (BT && PT && PT->isVoidPointerType() &&
+          PT->getPointeeType().isConstQualified() &&
+          (BT->getKind() == BuiltinType::UInt ||
+           BT->getKind() == BuiltinType::ULong))
+        SanOpts.Mask &= ~SanitizerKind::CFIUnrelatedCast;
+    }
+  }
+
   // Apply xray attributes to the function (as a string, for now)
   if (D && ShouldXRayInstrumentFunction()) {
     if (const auto *XRayAttr = D->getAttr<XRayInstrumentAttr>()) {
Index: test/CodeGen/cfi-unrelated-cast.cpp
===================================================================
--- /dev/null
+++ test/CodeGen/cfi-unrelated-cast.cpp
@@ -0,0 +1,32 @@
+// STL allocators should not have unrelated-cast tests applied
+// RUN: %clang_cc1 -flto -fvisibility hidden -fsanitize=cfi-unrelated-cast -emit-llvm -o - %s | FileCheck %s
+
+template<class T>
+class myalloc {
+ public:
+  // CHECK: define{{.*}}allocate
+  // CHECK-NOT: llvm.type.test
+  T *allocate(unsigned int sz, const void *ptr = 0) {
+    return (T*)ptr;
+  }
+
+  // CHECK: define{{.*}}differentName
+  // CHECK: llvm.type.test
+  T *differentName(unsigned int sz, const void *ptr = 0) {
+    return (T*)ptr;
+  }
+};
+
+class C1 {
+  virtual void f() {}
+};
+
+C1 *f1() {
+  myalloc<C1> allocator;
+  return allocator.allocate(16);
+}
+
+C1 *f2() {
+  myalloc<C1> allocator;
+  return allocator.differentName(16);
+}