diff --git a/clang-tools-extra/clangd/Hover.cpp b/clang-tools-extra/clangd/Hover.cpp
--- a/clang-tools-extra/clangd/Hover.cpp
+++ b/clang-tools-extra/clangd/Hover.cpp
@@ -13,6 +13,7 @@
 #include "FindTarget.h"
 #include "FormattedString.h"
 #include "Logger.h"
+#include "ParsedAST.h"
 #include "Selection.h"
 #include "SourceCode.h"
 #include "index/SymbolCollector.h"
@@ -21,13 +22,18 @@
 #include "clang/AST/Decl.h"
 #include "clang/AST/DeclBase.h"
 #include "clang/AST/DeclTemplate.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/ExprCXX.h"
 #include "clang/AST/PrettyPrinter.h"
 #include "clang/AST/Type.h"
 #include "clang/Index/IndexSymbol.h"
+#include "llvm/ADT/None.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Casting.h"
 #include "llvm/Support/raw_ostream.h"
 #include <string>
 
@@ -421,6 +427,43 @@
   }
   return HI;
 }
+
+// Generates hover info for string literals and evaluatable expressions.
+//  FIXME: Support hover for user-defined literals.
+llvm::Optional<HoverInfo> getHoverContents(const Expr *E, ParsedAST &AST) {
+  // There's not much value in hovering over "42" and getting a hover card
+  // saying "42 is an int", similar for other literals.
+  // Unfortunately there's no common base Literal classes inherits from
+  // (apart from Expr), therefore this is a nasty blacklist.
+  if (llvm::isa<CharacterLiteral>(E) || llvm::isa<CompoundLiteralExpr>(E) ||
+      llvm::isa<CXXBoolLiteralExpr>(E) || llvm::isa<CXXNullPtrLiteralExpr>(E) ||
+      llvm::isa<FixedPointLiteral>(E) || llvm::isa<FloatingLiteral>(E) ||
+      llvm::isa<ImaginaryLiteral>(E) || llvm::isa<IntegerLiteral>(E) ||
+      llvm::isa<UserDefinedLiteral>(E))
+    return llvm::None;
+
+  HoverInfo HI;
+  // For string literals we choose to show the type, which contains the
+  // length.
+  if (auto *SL = llvm::dyn_cast<StringLiteral>(E)) {
+    HI.Type = E->getType().getAsString();
+    // Not much value in repeating the literal's value, as user is
+    // directly hovering over it.
+    return HI;
+  }
+
+  // For expressions we currently print the type and the value, iff it is
+  // evaluatable.
+  if (auto Val = printExprValue(E, AST.getASTContext())) {
+    auto Policy =
+        printingPolicyForDecls(AST.getASTContext().getPrintingPolicy());
+    Policy.SuppressTagKeyword = true;
+    HI.Type = E->getType().getAsString(Policy);
+    HI.Value = *Val;
+    return HI;
+  }
+  return llvm::None;
+}
 } // namespace
 
 llvm::Optional<HoverInfo> getHover(ParsedAST &AST, Position Pos,
@@ -450,11 +493,11 @@
         // Look for a close enclosing expression to show the value of.
         if (!HI->Value)
           HI->Value = printExprValue(N, AST.getASTContext());
+      } else if (const Expr *E = N->ASTNode.get<Expr>()) {
+        HI = getHoverContents(E, AST);
       }
       // FIXME: support hovers for other nodes?
-      //  - certain expressions (sizeof etc)
       //  - built-in types
-      //  - literals (esp user-defined)
     }
   }
 
diff --git a/clang-tools-extra/clangd/unittests/HoverTests.cpp b/clang-tools-extra/clangd/unittests/HoverTests.cpp
--- a/clang-tools-extra/clangd/unittests/HoverTests.cpp
+++ b/clang-tools-extra/clangd/unittests/HoverTests.cpp
@@ -601,6 +601,18 @@
       R"cpp(// non-named decls don't get hover. Don't crash!
             ^static_assert(1, "");
           )cpp",
+      R"cpp(// non-evaluatable expr
+          template <typename T> void foo() {
+            (void)[[size^of]](T);
+          })cpp",
+      // literals
+      "auto x = t^rue;",
+      "auto x = '^A';",
+      "auto x = ^(int){42};",
+      "auto x = ^42.;",
+      "auto x = ^42.0i;",
+      "auto x = ^42;",
+      "auto x = ^nullptr;",
   };
 
   for (const auto &Test : Tests) {
@@ -1548,6 +1560,28 @@
             HI.ReturnType = "int";
             HI.Parameters.emplace();
           }},
+      {
+          R"cpp(// sizeof expr
+          void foo() {
+            (void)[[size^of]](char);
+          })cpp",
+          [](HoverInfo &HI) {
+            HI.Type = "unsigned long";
+            HI.Value = "1";
+          }},
+      {
+          R"cpp(// alignof expr
+          void foo() {
+            (void)[[align^of]](char);
+          })cpp",
+          [](HoverInfo &HI) {
+            HI.Type = "unsigned long";
+            HI.Value = "1";
+          }},
+      {
+          R"cpp(// string literals
+          auto x = [[^"asdf"]];)cpp",
+          [](HoverInfo &HI) { HI.Type = "const char [5]"; }},
   };
 
   // Create a tiny index, so tests above can verify documentation is fetched.