diff --git a/.gitmodules b/.gitmodules
index 5f2e8272cd2..a9210cfc69e 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -37,7 +37,7 @@
 [submodule "src/llvm-project"]
 	path = src/llvm-project
 	url = https://github.com/rust-lang/llvm-project.git
-	branch = rustc/9.0-2019-12-19
+	branch = rustc/10.0-2020-05-05
 [submodule "src/doc/embedded-book"]
 	path = src/doc/embedded-book
 	url = https://github.com/rust-embedded/book.git
diff --git a/src/bootstrap/native.rs b/src/bootstrap/native.rs
index 446017f1fab..5b6e9534843 100644
--- a/src/bootstrap/native.rs
+++ b/src/bootstrap/native.rs
@@ -520,6 +520,10 @@ impl Step for Lld {
                 .define("LLVM_TABLEGEN_EXE", llvm_config.with_file_name("llvm-tblgen"));
         }
 
+        // Explicitly set C++ standard, because upstream doesn't do so
+        // for standalone builds.
+        cfg.define("CMAKE_CXX_STANDARD", "14");
+
         cfg.build();
 
         t!(File::create(&done_stamp));
diff --git a/src/llvm-project b/src/llvm-project
index 246dfcd1c86..943dbddc8e0 160000
--- a/src/llvm-project
+++ b/src/llvm-project
@@ -1 +1 @@
-Subproject commit 246dfcd1c864d4eab417f74d3599f061d01cb3ae
+Subproject commit 943dbddc8e0869a382c4e1b2c135a40e28cf605c