Index: clang/lib/AST/Interp/ByteCodeExprGen.cpp
===================================================================
--- clang/lib/AST/Interp/ByteCodeExprGen.cpp
+++ clang/lib/AST/Interp/ByteCodeExprGen.cpp
@@ -319,19 +319,29 @@
   if (!visit(LHS) || !visit(RHS))
     return false;
 
+  // For languages such as C, cast the result of one
+  // of our comparision opcodes to T (which is usually int).
+  auto MaybeCastToBool = [this, T, BO](bool Result) {
+    if (!Result)
+      return false;
+    if (T != PT_Bool)
+      return this->emitCast(PT_Bool, *T, BO);
+    return true;
+  };
+
   switch (Op) {
   case BO_EQ:
-    return this->emitEQ(*LT, BO);
+    return MaybeCastToBool(this->emitEQ(*LT, BO));
   case BO_NE:
-    return this->emitNE(*LT, BO);
+    return MaybeCastToBool(this->emitNE(*LT, BO));
   case BO_LT:
-    return this->emitLT(*LT, BO);
+    return MaybeCastToBool(this->emitLT(*LT, BO));
   case BO_LE:
-    return this->emitLE(*LT, BO);
+    return MaybeCastToBool(this->emitLE(*LT, BO));
   case BO_GT:
-    return this->emitGT(*LT, BO);
+    return MaybeCastToBool(this->emitGT(*LT, BO));
   case BO_GE:
-    return this->emitGE(*LT, BO);
+    return MaybeCastToBool(this->emitGE(*LT, BO));
   case BO_Sub:
     if (T == PT_Float)
       return this->emitSubf(getRoundingMode(BO), BO);
Index: clang/test/AST/Interp/c.c
===================================================================
--- /dev/null
+++ clang/test/AST/Interp/c.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -verify %s
+// RUN: %clang_cc1 -verify=ref %s
+
+/// expected-no-diagnostics
+/// ref-no-diagnostics
+
+_Static_assert(1, "");
+_Static_assert(0 != 1, "");
+_Static_assert(1.0 == 1.0, "");
+_Static_assert( (5 > 4) + (3 > 2) == 2, "");