diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -1747,6 +1747,26 @@
     FuncAttrs.addAttribute(llvm::Attribute::NoUnwind);
 }
 
+static void AddAttributesFromAssumes(llvm::AttrBuilder &FuncAttrs,
+                                     const Decl *Callee, const Decl *Caller,
+                                     bool AssumptionOnCallSite) {
+  if (!Callee)
+    return;
+
+  SmallVector<StringRef, 4> Attrs;
+
+  for (const AssumptionAttr *AA : Callee->specific_attrs<AssumptionAttr>())
+    AA->getAssumption().split(Attrs, ",");
+
+  if (Caller && Caller->hasAttrs() && AssumptionOnCallSite)
+    for (const AssumptionAttr *AA : Caller->specific_attrs<AssumptionAttr>())
+      AA->getAssumption().split(Attrs, ",");
+
+  if (!Attrs.empty())
+    FuncAttrs.addAttribute(llvm::AssumptionAttrKey,
+                           llvm::join(Attrs.begin(), Attrs.end(), ","));
+}
+
 bool CodeGenModule::MayDropFunctionReturn(const ASTContext &Context,
                                           QualType ReturnType) {
   // We can't just discard the return value for a record type with a
@@ -1997,12 +2017,10 @@
 ///     attributes that restrict how the frontend generates code must be
 ///     added here rather than getDefaultFunctionAttributes.
 ///
-void CodeGenModule::ConstructAttributeList(StringRef Name,
-                                           const CGFunctionInfo &FI,
-                                           CGCalleeInfo CalleeInfo,
-                                           llvm::AttributeList &AttrList,
-                                           unsigned &CallingConv,
-                                           bool AttrOnCallSite, bool IsThunk) {
+void CodeGenModule::ConstructAttributeList(
+    StringRef Name, const CGFunctionInfo &FI, CGCalleeInfo CalleeInfo,
+    llvm::AttributeList &AttrList, unsigned &CallingConv, bool AttrOnCallSite,
+    bool IsThunk, const Decl *Caller) {
   llvm::AttrBuilder FuncAttrs;
   llvm::AttrBuilder RetAttrs;
 
@@ -2020,6 +2038,13 @@
 
   const Decl *TargetDecl = CalleeInfo.getCalleeDecl().getDecl();
 
+  // Only attach assumptions to call sites in OpenMP mode.
+  bool AssumptionOnCallSite = getLangOpts().OpenMP && AttrOnCallSite;
+
+  // Attach assumption attributes to the declaration. If this is a call
+  // site, attach assumptions from the caller to the call as well.
+  AddAttributesFromAssumes(FuncAttrs, TargetDecl, Caller, AssumptionOnCallSite);
+
   bool HasOptnone = false;
   // The NoBuiltinAttr attached to the target FunctionDecl.
   const NoBuiltinAttr *NBA = nullptr;
@@ -2119,18 +2144,6 @@
                                llvm::toStringRef(CodeGenOpts.UniformWGSize));
       }
     }
-
-    std::string AssumptionValueStr;
-    for (AssumptionAttr *AssumptionA :
-         TargetDecl->specific_attrs<AssumptionAttr>()) {
-      std::string AS = AssumptionA->getAssumption().str();
-      if (!AS.empty() && !AssumptionValueStr.empty())
-        AssumptionValueStr += ",";
-      AssumptionValueStr += AS;
-    }
-
-    if (!AssumptionValueStr.empty())
-      FuncAttrs.addAttribute(llvm::AssumptionAttrKey, AssumptionValueStr);
   }
 
   // Attach "no-builtins" attributes to:
@@ -5165,7 +5178,7 @@
   CGM.ConstructAttributeList(CalleePtr->getName(), CallInfo,
                              Callee.getAbstractInfo(), Attrs, CallingConv,
                              /*AttrOnCallSite=*/true,
-                             /*IsThunk=*/false);
+                             /*IsThunk=*/false, CurFuncDecl);
 
   if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(CurFuncDecl))
     if (FD->hasAttr<StrictFPAttr>())
diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp
--- a/clang/lib/CodeGen/CGStmt.cpp
+++ b/clang/lib/CodeGen/CGStmt.cpp
@@ -26,6 +26,7 @@
 #include "clang/Basic/TargetInfo.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/IR/Assumptions.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/InlineAsm.h"
 #include "llvm/IR/Intrinsics.h"
@@ -2209,6 +2210,20 @@
       Result.addFnAttr(llvm::Attribute::ReadOnly);
   }
 
+  // Attach OpenMP assumption attributes from the caller, if they exist.
+  if (CGF.CGM.getLangOpts().OpenMP) {
+    SmallVector<StringRef, 4> Attrs;
+
+    for (const AssumptionAttr *AA :
+         CGF.CurFuncDecl->specific_attrs<AssumptionAttr>())
+      AA->getAssumption().split(Attrs, ",");
+
+    if (!Attrs.empty())
+      Result.addFnAttr(
+          llvm::Attribute::get(CGF.getLLVMContext(), llvm::AssumptionAttrKey,
+                               llvm::join(Attrs.begin(), Attrs.end(), ",")));
+  }
+
   // Slap the source location of the inline asm into a !srcloc metadata on the
   // call.
   if (const auto *gccAsmStmt = dyn_cast<GCCAsmStmt>(&S))
diff --git a/clang/lib/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
--- a/clang/lib/CodeGen/CGVTables.cpp
+++ b/clang/lib/CodeGen/CGVTables.cpp
@@ -428,7 +428,7 @@
   llvm::AttributeList Attrs;
   CGM.ConstructAttributeList(Callee.getCallee()->getName(), *CurFnInfo, GD,
                              Attrs, CallingConv, /*AttrOnCallSite=*/true,
-                             /*IsThunk=*/false);
+                             /*IsThunk=*/false, CurFuncDecl);
   Call->setAttributes(Attrs);
   Call->setCallingConv(static_cast<llvm::CallingConv::ID>(CallingConv));
 
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -1200,7 +1200,8 @@
   void ConstructAttributeList(StringRef Name, const CGFunctionInfo &Info,
                               CGCalleeInfo CalleeInfo,
                               llvm::AttributeList &Attrs, unsigned &CallingConv,
-                              bool AttrOnCallSite, bool IsThunk);
+                              bool AttrOnCallSite, bool IsThunk,
+                              const Decl *Caller = nullptr);
 
   /// Adds attributes to F according to our CodeGenOptions and LangOptions, as
   /// though we had emitted it ourselves.  We remove any attributes on F that
diff --git a/clang/test/OpenMP/assumes_codegen.cpp b/clang/test/OpenMP/assumes_codegen.cpp
--- a/clang/test/OpenMP/assumes_codegen.cpp
+++ b/clang/test/OpenMP/assumes_codegen.cpp
@@ -67,6 +67,20 @@
 }
 #pragma omp end assumes
 
+void no_assume() {
+  foo();
+}
+
+#pragma omp begin assumes ext_call_site
+void assume() {
+  foo();
+}
+
+void assembly() {
+  asm ("nop");
+}
+#pragma omp end assumes ext_call_site
+
 // AST:      void foo() __attribute__((assume("omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses"))) __attribute__((assume("omp_no_openmp"))) {
 // AST-NEXT: }
 // AST-NEXT: class BAR {
@@ -115,29 +129,41 @@
 // CHECK: define{{.*}} void @_Z3barv()
 // CHECK-SAME: [[attr1:#[0-9]]]
 // CHECK:   call{{.*}} @_ZN3BARC1Ev(%class.BAR*{{.*}} %b)
-// CHECK-SAME: [[attr9:#[0-9]]]
+// CHECK-SAME: [[attr10:#[0-9]]]
 // CHECK: define{{.*}} void @_ZN3BARC1Ev(%class.BAR*{{.*}} %this)
 // CHECK-SAME: [[attr2:#[0-9]]]
 // CHECK:   call{{.*}} @_ZN3BARC2Ev(%class.BAR*{{.*}} %this1)
-// CHECK-SAME: [[attr9]]
+// CHECK-SAME: [[attr10]]
 // CHECK: define{{.*}} void @_ZN3BARC2Ev(%class.BAR*{{.*}} %this)
 // CHECK-SAME: [[attr3:#[0-9]]]
 // CHECK: define{{.*}} void @_Z3bazv()
 // CHECK-SAME: [[attr4:#[0-9]]]
 // CHECK:   call{{.*}} @_ZN3BAZIfEC1Ev(%class.BAZ*{{.*}} %b)
-// CHECK-SAME: [[attr10:#[0-9]]]
+// CHECK-SAME: [[attr11:#[0-9]]]
 // CHECK: define{{.*}} void @_ZN3BAZIfEC1Ev(%class.BAZ*{{.*}} %this)
 // CHECK-SAME: [[attr5:#[0-9]]]
 // CHECK:   call{{.*}} @_ZN3BAZIfEC2Ev(%class.BAZ*{{.*}} %this1)
-// CHECK-SAME: [[attr10]]
+// CHECK-SAME: [[attr12:#[0-9]]]
 // CHECK: define{{.*}} void @_ZN3BAZIfEC2Ev(%class.BAZ*{{.*}} %this)
 // CHECK-SAME: [[attr6:#[0-9]]]
 // CHECK: define{{.*}} i32 @_Z12lambda_outerv()
 // CHECK-SAME: [[attr7:#[0-9]]]
 // CHECK: call{{.*}} @"_ZZ12lambda_outervENK3$_0clEv"
-// CHECK-SAME: [[attr11:#[0-9]]]
+// CHECK-SAME: [[attr13:#[0-9]]]
 // CHECK: define{{.*}} i32 @"_ZZ12lambda_outervENK3$_0clEv"(%class.anon*{{.*}} %this)
 // CHECK-SAME: [[attr8:#[0-9]]]
+// CHECK: define{{.*}} void @_Z9no_assumev()
+// CHECK-SAME: [[attr0:#[0-9]]]
+// CHECK: call{{.*}} @_Z3foov()
+// CHECK-SAME: [[attr14:#[0-9]]]
+// CHECK: define{{.*}} void @_Z6assumev()
+// CHECK-SAME: [[attr9:#[0-9]]]
+// CHECK: call{{.*}} @_Z3foov()
+// CHECK-SAME: [[attr15:#[0-9]]]
+// CHECK: define{{.*}} void @_Z8assemblyv()
+// CHECK-SAME: [[attr9:#[0-9]]]
+// CHECK: call{{.*}} void asm sideeffect "nop", "~{dirflag},~{fpsr},~{flags}"()
+// CHECK-SAME: [[attr16:#[0-9]]]
 
 // CHECK:     attributes [[attr0]]
 // CHECK-SAME:  "llvm.assume"="omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp"
@@ -158,8 +184,18 @@
 // CHECK:     attributes [[attr8]]
 // CHECK-SAME:  "llvm.assume"="ompx_lambda_assumption,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp"
 // CHECK:     attributes [[attr9]]
-// CHECK-SAME:  "llvm.assume"="ompx_range_bar_only,ompx_range_bar_only_2,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp"
+// CHECK-SAME:  "llvm.assume"="ompx_call_site,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp"
 // CHECK:     attributes [[attr10]]
-// CHECK-SAME:  "llvm.assume"="ompx_1234,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp"
+// CHECK-SAME:  "llvm.assume"="ompx_range_bar_only,ompx_range_bar_only_2,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp,ompx_range_bar_only,ompx_range_bar_only_2,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp"
 // CHECK:     attributes [[attr11]]
-// CHECK-SAME:  "llvm.assume"="ompx_lambda_assumption,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp"
+// CHECK-SAME:  "llvm.assume"="ompx_1234,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp,ompx_1234,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp,ompx_1234,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp"
+// CHECK:     attributes [[attr12]]
+// CHECK-SAME:  "llvm.assume"="ompx_1234,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp,ompx_1234,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp"
+// CHECK:     attributes [[attr13]]
+// CHECK-SAME:  "llvm.assume"="ompx_lambda_assumption,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp,ompx_lambda_assumption,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp"
+// CHECK:     attributes [[attr14]]
+// CHECK-SAME:  "llvm.assume"="omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp"
+// CHECK:     attributes [[attr15]]
+// CHECK-SAME:  "llvm.assume"="omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp,ompx_call_site,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp"
+// CHECK:     attributes [[attr16]]
+// CHECK-SAME:  "llvm.assume"="ompx_call_site,omp_no_openmp_routines,ompx_another_warning,ompx_after_invalid_clauses,omp_no_openmp"
diff --git a/clang/test/OpenMP/assumes_include_nvptx.cpp b/clang/test/OpenMP/assumes_include_nvptx.cpp
--- a/clang/test/OpenMP/assumes_include_nvptx.cpp
+++ b/clang/test/OpenMP/assumes_include_nvptx.cpp
@@ -24,7 +24,7 @@
 // CHECK:       attributes [[attr1]]
 // CHECK-SAME:  "llvm.assume"="ompx_check_that_this_is_attached_to_included_functions_and_template_instantiations"
 // CHECK:       attributes [[attr2]]
-// CHECK-SAME:  "llvm.assume"="ompx_check_that_this_is_attached_to_included_functions_and_template_instantiations"
+// CHECK-SAME:  "llvm.assume"="ompx_check_that_this_is_attached_to_included_functions_and_template_instantiations,ompx_check_that_this_is_attached_to_included_functions_and_template_instantiations"
 
 
 template <typename T>