diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -398,6 +398,8 @@
   PCH or modules. When Clang hits this limit, it now produces notes mentioning
   which header and source files are consuming large amounts of this space.
   ``#pragma clang __debug sloc_usage`` can also be used to request this report.
+- Clang will implicitly add ``#include "stdc-predef.h"`` on musl-based systems
+  as GCC does.
 
 Non-comprehensive list of changes in this release
 -------------------------------------------------
diff --git a/clang/lib/Driver/ToolChains/Linux.cpp b/clang/lib/Driver/ToolChains/Linux.cpp
--- a/clang/lib/Driver/ToolChains/Linux.cpp
+++ b/clang/lib/Driver/ToolChains/Linux.cpp
@@ -636,6 +636,12 @@
 
   if (!DriverArgs.hasArg(options::OPT_nobuiltininc) && getTriple().isMusl())
     addSystemInclude(DriverArgs, CC1Args, ResourceDirInclude);
+
+  // Add an implicit include for musl-based non-free-standing systems.
+  if (!DriverArgs.hasArg(options::OPT_ffreestanding) && getTriple().isMusl()) {
+    CC1Args.push_back("-include");
+    CC1Args.push_back("stdc-predef.h");
+  }
 }
 
 void Linux::addLibStdCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
diff --git a/clang/test/Driver/Inputs/stdc-predef/usr/include/stdc-predef.h b/clang/test/Driver/Inputs/stdc-predef/usr/include/stdc-predef.h
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/Inputs/stdc-predef/usr/include/stdc-predef.h
@@ -0,0 +1,4 @@
+#ifndef	_STDC_PREDEF_H
+#define	_STDC_PREDEF_H	1
+#define DUMMY_STDC_PREDEF 1
+#endif
diff --git a/clang/test/Driver/stdc-predef.c b/clang/test/Driver/stdc-predef.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/stdc-predef.c
@@ -0,0 +1,62 @@
+// Test that clang preincludes stdc-predef.h, if we are using libc that does not
+// pre-include it, e.g. Musl
+
+// Musl-based systems need this addition include.
+//
+// RUN: %clang %s -### -c 2>&1 \
+// RUN: -target x86_64-unknown-linux-musl \
+// RUN: --sysroot=%S/Inputs/stdc-predef \
+// RUN: | FileCheck -check-prefix CHECK-CPP-FLAG %s
+
+// GNU-based systems do not need this addition include.
+//
+// RUN: %clang %s -### -c -ffreestanding 2>&1 \
+// RUN: -target x86_64-unknown-linux-gnu \
+// RUN: --sysroot=%S/Inputs/stdc-predef \
+// RUN: | FileCheck --implicit-check-not "stdc-predef.h" %s
+
+// Freestanding compilations do not need this addition include.
+//
+// RUN: %clang %s -### -c 2>&1 \
+// RUN: -target x86_64-unknown-linux-musl -ffreestanding \
+// RUN: --sysroot=%S/Inputs/stdc-predef \
+// RUN: | FileCheck --implicit-check-not "stdc-predef.h" %s
+
+// Because this behavior is implemented by adding preprocessor flags in the 
+// driver, disabling preprocessing means the include flag should not appear.
+//
+// RUN: %clang -x cpp-output %s -### -c 2>&1 \
+// RUN: -target x86_64-unknown-linux-musl \
+// RUN: --sysroot=%S/Inputs/stdc-predef \
+// RUN: | FileCheck --implicit-check-not "stdc-predef.h" %s
+
+// This behavior should appear in all files clang accepted that use the C 
+// preprocessor, including C, C++ and Objective-C files, as long as the system 
+// uses musl.
+//
+// RUN: %clang -x objective-c %s -### -c 2>&1 \
+// RUN: -target x86_64-unknown-linux-musl \
+// RUN: --sysroot=%S/Inputs/stdc-predef \
+// RUN: | FileCheck -check-prefix CHECK-CPP-FLAG %s
+
+// If a musl-based system does not have this header, give an error at line 1.
+//
+// RUN: %clang %s -c -Xclang -verify=expected 2>&1 \
+// RUN: -target x86_64-unknown-linux-musl \
+// RUN: --sysroot=%S/Inputs/basic_linux_tree 
+// expected-error@1 {{'stdc-predef.h' file not found}}
+
+// Check if the file is really included by macro.
+//
+// RUN: %clang %s -c -Xclang -verify=ok -DCHECK_DUMMY=1 \
+// RUN: -target x86_64-unknown-linux-musl \
+// RUN: --sysroot=%S/Inputs/stdc-predef 
+// ok-no-diagnostics
+
+// CHECK-CPP-FLAG: "-include" "stdc-predef.h"
+int i;
+#if CHECK_DUMMY
+#if !DUMMY_STDC_PREDEF 
+  #error "Expected macro symbol DUMMY_STDC_PREDEF is not defined."
+#endif
+#endif
diff --git a/clang/test/Driver/stdc-predef.i b/clang/test/Driver/stdc-predef.i
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/stdc-predef.i
@@ -0,0 +1,9 @@
+// The automatic preinclude of stdc-predef.h should not occur if
+// the source filename indicates a preprocessed file.
+//
+// RUN: %clang %s -### -c 2>&1 \
+// RUN: --sysroot=%S/Inputs/stdc-predef \
+// RUN: -target x86_64-unknown-linux-musl \
+// RUN: | FileCheck --implicit-check-not "stdc-predef.h" %s
+
+int i;