diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -1943,6 +1943,11 @@
     This attribute indicates that the inliner should never inline this
     function in any situation. This attribute may not be used together
     with the ``alwaysinline`` attribute.
+``noipa``
+    Disables any interprocedural analysis that inspects the definition of this
+    function. Equivalent to moving this function definition to a separate,
+    optimizer-opaque, module. Any attributes on the function are still respected
+    (as they would be if they remained on a function declaration in this module).
 ``nomerge``
     This attribute indicates that calls to this function should never be merged
     during optimization. For example, it will prevent tail merging otherwise
diff --git a/llvm/include/llvm/Bitcode/LLVMBitCodes.h b/llvm/include/llvm/Bitcode/LLVMBitCodes.h
--- a/llvm/include/llvm/Bitcode/LLVMBitCodes.h
+++ b/llvm/include/llvm/Bitcode/LLVMBitCodes.h
@@ -714,6 +714,7 @@
   ATTR_KIND_MEMORY = 86,
   ATTR_KIND_NOFPCLASS = 87,
   ATTR_KIND_OPTIMIZE_FOR_DEBUGGING = 88,
+  ATTR_KIND_NO_INTERPROCEDURAL_ANALYSIS = 89,
 };
 
 enum ComdatSelectionKindCodes {
diff --git a/llvm/include/llvm/IR/Attributes.td b/llvm/include/llvm/IR/Attributes.td
--- a/llvm/include/llvm/IR/Attributes.td
+++ b/llvm/include/llvm/IR/Attributes.td
@@ -157,6 +157,9 @@
 /// inline=never.
 def NoInline : EnumAttr<"noinline", [FnAttr]>;
 
+/// Do not do interprocedural analysis or optimization including this function
+def NoIPA : EnumAttr<"noipa", [FnAttr]>;
+
 /// Function is called early and/or often, so lazy binding isn't worthwhile.
 def NonLazyBind : EnumAttr<"nonlazybind", [FnAttr]>;
 
diff --git a/llvm/include/llvm/IR/GlobalValue.h b/llvm/include/llvm/IR/GlobalValue.h
--- a/llvm/include/llvm/IR/GlobalValue.h
+++ b/llvm/include/llvm/IR/GlobalValue.h
@@ -130,7 +130,7 @@
   /// Returns true if the definition of this global may be replaced by a
   /// differently optimized variant of the same source level function at link
   /// time.
-  bool mayBeDerefined() const {
+  bool mayBeDerefinedOrNoIPA() const {
     switch (getLinkage()) {
     case WeakODRLinkage:
     case LinkOnceODRLinkage:
@@ -149,7 +149,7 @@
       // nobuiltin due to attributes at call-sites. To avoid applying IPO based
       // on nobuiltin semantics, treat such function definitions as maybe
       // derefined.
-      return isInterposable() || isNobuiltinFnDef();
+      return isInterposable() || isNobuiltinFnDef() || isNoipaFnDef();
     }
 
     llvm_unreachable("Fully covered switch above!");
@@ -159,6 +159,10 @@
   /// attribute.
   bool isNobuiltinFnDef() const;
 
+  /// Returns true if the global is a function definition with the noipa
+  /// attribute.
+  bool isNoipaFnDef() const;
+
 protected:
   /// The intrinsic ID for this subclass (which must be a Function).
   ///
@@ -483,7 +487,7 @@
   /// visible variant is *a* correct implementation of the original source
   /// function; it just isn't the *only* correct implementation.
   bool isDefinitionExact() const {
-    return !mayBeDerefined();
+    return !mayBeDerefinedOrNoIPA();
   }
 
   /// Return true if this global has an exact defintion.
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -2058,6 +2058,8 @@
     return Attribute::Hot;
   case bitc::ATTR_KIND_PRESPLIT_COROUTINE:
     return Attribute::PresplitCoroutine;
+  case bitc::ATTR_KIND_NO_INTERPROCEDURAL_ANALYSIS:
+    return Attribute::NoIPA;
   }
 }
 
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -823,6 +823,8 @@
     return bitc::ATTR_KIND_MUSTPROGRESS;
   case Attribute::PresplitCoroutine:
     return bitc::ATTR_KIND_PRESPLIT_COROUTINE;
+  case Attribute::NoIPA:
+    return bitc::ATTR_KIND_NO_INTERPROCEDURAL_ANALYSIS;
   case Attribute::EndAttrKinds:
     llvm_unreachable("Can not encode end-attribute kinds marker.");
   case Attribute::None:
diff --git a/llvm/lib/IR/Globals.cpp b/llvm/lib/IR/Globals.cpp
--- a/llvm/lib/IR/Globals.cpp
+++ b/llvm/lib/IR/Globals.cpp
@@ -270,6 +270,13 @@
   return F->hasFnAttribute(Attribute::NoBuiltin);
 }
 
+bool GlobalValue::isNoipaFnDef() const {
+  const Function *F = dyn_cast<Function>(this);
+  if (!F || F->empty())
+    return false;
+  return F->hasFnAttribute(Attribute::NoIPA);
+}
+
 bool GlobalValue::isDeclaration() const {
   // Globals are definitions if they have an initializer.
   if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(this))
diff --git a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
--- a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -743,7 +743,7 @@
   for (Function *F : SCCNodes) {
     // We can infer and propagate function attributes only when we know that the
     // definition we'll get at link time is *exactly* the definition we see now.
-    // For more details, see GlobalValue::mayBeDerefined.
+    // For more details, see GlobalValue::mayBeDerefinedOrNoIPA.
     if (!F->hasExactDefinition())
       continue;
 
@@ -860,7 +860,7 @@
   for (Function *F : SCCNodes) {
     // We can infer and propagate function attributes only when we know that the
     // definition we'll get at link time is *exactly* the definition we see now.
-    // For more details, see GlobalValue::mayBeDerefined.
+    // For more details, see GlobalValue::mayBeDerefinedOrNoIPA.
     if (!F->hasExactDefinition())
       continue;
 
@@ -1111,7 +1111,7 @@
 
     // We can infer and propagate function attributes only when we know that the
     // definition we'll get at link time is *exactly* the definition we see now.
-    // For more details, see GlobalValue::mayBeDerefined.
+    // For more details, see GlobalValue::mayBeDerefinedOrNoIPA.
     if (!F->hasExactDefinition())
       return;
 
@@ -1223,7 +1223,7 @@
 
     // We can infer and propagate function attributes only when we know that the
     // definition we'll get at link time is *exactly* the definition we see now.
-    // For more details, see GlobalValue::mayBeDerefined.
+    // For more details, see GlobalValue::mayBeDerefinedOrNoIPA.
     if (!F->hasExactDefinition())
       return;
 
@@ -1679,7 +1679,7 @@
 static bool functionWillReturn(const Function &F) {
   // We can infer and propagate function attributes only when we know that the
   // definition we'll get at link time is *exactly* the definition we see now.
-  // For more details, see GlobalValue::mayBeDerefined.
+  // For more details, see GlobalValue::mayBeDerefinedOrNoIPA.
   if (!F.hasExactDefinition())
     return false;
 
diff --git a/llvm/lib/Transforms/Utils/CodeExtractor.cpp b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
--- a/llvm/lib/Transforms/Utils/CodeExtractor.cpp
+++ b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
@@ -946,6 +946,7 @@
       case Attribute::OptimizeForDebugging:
       case Attribute::OptForFuzzing:
       case Attribute::OptimizeNone:
+      case Attribute::NoIPA:
       case Attribute::OptimizeForSize:
       case Attribute::SafeStack:
       case Attribute::ShadowCallStack:
diff --git a/llvm/test/Bitcode/attributes.ll b/llvm/test/Bitcode/attributes.ll
--- a/llvm/test/Bitcode/attributes.ll
+++ b/llvm/test/Bitcode/attributes.ll
@@ -517,6 +517,12 @@
         ret void;
 }
 
+define void @f90() noipa
+; CHECK: define void @f90() [[NOIPA:#[0-9]+]]
+{
+  ret void
+}
+
 ; CHECK: attributes #0 = { noreturn }
 ; CHECK: attributes #1 = { nounwind }
 ; CHECK: attributes #2 = { memory(none) }
@@ -573,4 +579,5 @@
 ; CHECK: attributes [[FNRETTHUNKEXTERN]] = { fn_ret_thunk_extern }
 ; CHECK: attributes [[SKIPPROFILE]] = { skipprofile }
 ; CHECK: attributes [[OPTDEBUG]] = { optdebug }
+; CHECK: attributes [[NOIPA]] = { noipa }
 ; CHECK: attributes #[[NOBUILTIN]] = { nobuiltin }
diff --git a/llvm/unittests/IR/FunctionTest.cpp b/llvm/unittests/IR/FunctionTest.cpp
--- a/llvm/unittests/IR/FunctionTest.cpp
+++ b/llvm/unittests/IR/FunctionTest.cpp
@@ -486,4 +486,16 @@
   It = F->erase(F->begin(), F->end());
   EXPECT_EQ(F->size(), 0u);
 }
+
+TEST(FunctionTest, NoIPAInexact) {
+  LLVMContext Ctx;
+  std::unique_ptr<Module> M = parseIR(Ctx, R"(
+    define void @foo() { bb1: ret void }
+    define void @bar() #0 { bb1: ret void }
+    attributes #0 = { noipa }
+  )");
+  EXPECT_TRUE(M->getFunction("foo")->isDefinitionExact());
+  EXPECT_FALSE(M->getFunction("bar")->isDefinitionExact());
+}
+
 } // end namespace
diff --git a/llvm/utils/emacs/llvm-mode.el b/llvm/utils/emacs/llvm-mode.el
--- a/llvm/utils/emacs/llvm-mode.el
+++ b/llvm/utils/emacs/llvm-mode.el
@@ -24,7 +24,7 @@
    `(,(regexp-opt
        '("alwaysinline" "argmemonly" "allocsize" "builtin" "cold" "convergent" "dereferenceable" "dereferenceable_or_null" "hot" "immarg" "inaccessiblememonly"
          "inaccessiblemem_or_argmemonly" "inalloca" "inlinehint" "jumptable" "minsize" "mustprogress" "naked" "nobuiltin" "nonnull" "nocapture"
-         "nocallback" "nocf_check" "noduplicate" "nofree" "noimplicitfloat" "noinline" "nomerge" "nonlazybind" "noprofile" "noredzone" "noreturn"
+         "nocallback" "nocf_check" "noduplicate" "nofree" "noimplicitfloat" "noinline" "noipa" "nomerge" "nonlazybind" "noprofile" "noredzone" "noreturn"
          "norecurse" "nosync" "noundef" "nounwind" "nosanitize_bounds" "nosanitize_coverage" "null_pointer_is_valid" "optdebug" "optforfuzzing" "optnone" "optsize" "preallocated" "readnone" "readonly" "returned" "returns_twice"
          "shadowcallstack" "signext" "speculatable" "speculative_load_hardening" "ssp" "sspreq" "sspstrong" "safestack" "sanitize_address" "sanitize_hwaddress" "sanitize_memtag"
          "sanitize_thread" "sanitize_memory" "strictfp" "swifterror" "uwtable" "vscale_range" "willreturn" "writeonly" "zeroext") 'symbols) . font-lock-constant-face)
diff --git a/llvm/utils/kate/llvm.xml b/llvm/utils/kate/llvm.xml
--- a/llvm/utils/kate/llvm.xml
+++ b/llvm/utils/kate/llvm.xml
@@ -104,6 +104,7 @@
       <item> nofree </item>
       <item> noimplicitfloat </item>
       <item> noinline </item>
+      <item> noipa </item>
       <item> nomerge </item>
       <item> noprofile </item>
       <item> noredzone </item>
diff --git a/llvm/utils/vim/syntax/llvm.vim b/llvm/utils/vim/syntax/llvm.vim
--- a/llvm/utils/vim/syntax/llvm.vim
+++ b/llvm/utils/vim/syntax/llvm.vim
@@ -129,6 +129,7 @@
       \ nofree
       \ noimplicitfloat
       \ noinline
+      \ noipa
       \ nomerge
       \ nonlazybind
       \ nonnull
diff --git a/llvm/utils/vscode/llvm/syntaxes/ll.tmLanguage.yaml b/llvm/utils/vscode/llvm/syntaxes/ll.tmLanguage.yaml
--- a/llvm/utils/vscode/llvm/syntaxes/ll.tmLanguage.yaml
+++ b/llvm/utils/vscode/llvm/syntaxes/ll.tmLanguage.yaml
@@ -228,6 +228,7 @@
             \\bnofree\\b|\
             \\bnoimplicitfloat\\b|\
             \\bnoinline\\b|\
+            \\bnoipa\\b|\
             \\bnomerge\\b|\
             \\bnonlazybind\\b|\
             \\bnonnull\\b|\