diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -4486,7 +4486,8 @@
         }
 
         // Alignment calculations can wrap around if it's greater than 2**29.
-        unsigned MaximumAlignment = 536870912;
+        unsigned MaximumAlignment =
+            536870912; // See llvm::Value::MaximumAlignment
         if (I > MaximumAlignment)
           Diag(Arg->getExprLoc(), diag::warn_assume_aligned_too_great)
               << Arg->getSourceRange() << MaximumAlignment;
@@ -6215,7 +6216,7 @@
              << Arg->getSourceRange();
 
     // Alignment calculations can wrap around if it's greater than 2**29.
-    unsigned MaximumAlignment = 536870912;
+    unsigned MaximumAlignment = 536870912; // See llvm::Value::MaximumAlignment
     if (Result > MaximumAlignment)
       Diag(TheCall->getBeginLoc(), diag::warn_assume_aligned_too_great)
           << Arg->getSourceRange() << MaximumAlignment;
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -1627,7 +1627,7 @@
     }
 
     // Alignment calculations can wrap around if it's greater than 2**29.
-    unsigned MaximumAlignment = 536870912;
+    unsigned MaximumAlignment = 536870912; // See llvm::Value::MaximumAlignment
     if (I > MaximumAlignment)
       Diag(CI.getLoc(), diag::warn_assume_aligned_too_great)
           << CI.getRange() << MaximumAlignment;
diff --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -143,7 +143,7 @@
 }
 
 Attribute Attribute::getWithAlignment(LLVMContext &Context, Align A) {
-  assert(A <= 0x40000000 && "Alignment too large.");
+  assert(A <= llvm::Value::MaximumAlignment && "Alignment too large.");
   return get(Context, Alignment, A.value());
 }
 
@@ -1521,7 +1521,7 @@
   if (!Align)
     return *this;
 
-  assert(*Align <= 0x40000000 && "Alignment too large.");
+  assert(*Align <= llvm::Value::MaximumAlignment && "Alignment too large.");
 
   Attrs[Attribute::Alignment] = true;
   Alignment = Align;