diff --git a/src/shims/sync.rs b/src/shims/sync.rs
index 61346bfd85b..b8d9a88865e 100644
--- a/src/shims/sync.rs
+++ b/src/shims/sync.rs
@@ -6,26 +6,16 @@ use crate::*;
 
 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
-    // pthread_mutexattr_t is either 4 or 8 bytes, depending on the platform
-    // memory layout: store an i32 in the first four bytes equal to the
-    // corresponding libc mutex kind constant (i.e. PTHREAD_MUTEX_NORMAL)
-
     fn pthread_mutexattr_init(&mut self, attr_op: OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
-        // Ensure that the following write at an offset to the attr pointer is within bounds
-        assert_ptr_target_min_size(this, attr_op, 4)?;
-
         let attr = this.read_scalar(attr_op)?.not_undef()?;
         if this.is_null(attr)? {
             return this.eval_libc_i32("EINVAL");
         }
 
-        let attr_place = this.deref_operand(attr_op)?;
-        let i32_layout = this.layout_of(this.tcx.types.i32)?;
-        let kind_place = attr_place.offset(Size::ZERO, MemPlaceMeta::None, i32_layout, this)?;
         let default_kind = this.eval_libc("PTHREAD_MUTEX_DEFAULT")?;
-        this.write_scalar(default_kind, kind_place.into())?;
+        mutexattr_set_kind(this, attr_op, default_kind)?;
 
         Ok(0)
     }
@@ -37,22 +27,17 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     ) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
-        // Ensure that the following write at an offset to the attr pointer is within bounds
-        assert_ptr_target_min_size(this, attr_op, 4)?;
-
         let attr = this.read_scalar(attr_op)?.not_undef()?;
         if this.is_null(attr)? {
             return this.eval_libc_i32("EINVAL");
         }
 
         let kind = this.read_scalar(kind_op)?.not_undef()?;
-        if kind == this.eval_libc("PTHREAD_MUTEX_NORMAL")? ||
-                kind == this.eval_libc("PTHREAD_MUTEX_ERRORCHECK")? ||
-                kind == this.eval_libc("PTHREAD_MUTEX_RECURSIVE")? {
-            let attr_place = this.deref_operand(attr_op)?;
-            let i32_layout = this.layout_of(this.tcx.types.i32)?;
-            let kind_place = attr_place.offset(Size::ZERO, MemPlaceMeta::None, i32_layout, this)?;
-            this.write_scalar(kind, kind_place.into())?;
+        if kind == this.eval_libc("PTHREAD_MUTEX_NORMAL")?
+            || kind == this.eval_libc("PTHREAD_MUTEX_ERRORCHECK")?
+            || kind == this.eval_libc("PTHREAD_MUTEX_RECURSIVE")?
+        {
+            mutexattr_set_kind(this, attr_op, kind)?;
         } else {
             let einval = this.eval_libc_i32("EINVAL")?;
             return Ok(einval);
@@ -64,30 +49,16 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn pthread_mutexattr_destroy(&mut self, attr_op: OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
-        // Ensure that the following write at an offset to the attr pointer is within bounds
-        assert_ptr_target_min_size(this, attr_op, 4)?;
-
         let attr = this.read_scalar(attr_op)?.not_undef()?;
         if this.is_null(attr)? {
             return this.eval_libc_i32("EINVAL");
         }
 
-        let attr_place = this.deref_operand(attr_op)?;
-        let i32_layout = this.layout_of(this.tcx.types.i32)?;
-        let kind_place = attr_place.offset(Size::ZERO, MemPlaceMeta::None, i32_layout, this)?;
-        this.write_scalar(ScalarMaybeUndef::Undef, kind_place.into())?;
+        mutexattr_set_kind(this, attr_op, ScalarMaybeUndef::Undef)?;
 
         Ok(0)
     }
 
-    // pthread_mutex_t is between 24 and 48 bytes, depending on the platform
-    // memory layout:
-    // bytes 0-3: reserved for signature on macOS
-    // bytes 4-7: count of how many times this mutex has been locked, as a u32
-    // bytes 12-15: mutex kind, as an i32
-    // (the kind should be at this offset for compatibility with the static
-    // initializer macro)
-
     fn pthread_mutex_init(
         &mut self,
         mutex_op: OpTy<'tcx, Tag>,
@@ -95,34 +66,20 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     ) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
-        // Ensure that the following writes at offsets to the mutex pointer are within bounds
-        assert_ptr_target_min_size(this, mutex_op, 16)?;
-        // Ensure that the following read at an offset to the attr pointer is within bounds
-        assert_ptr_target_min_size(this, attr_op, 4)?;
-
         let mutex = this.read_scalar(mutex_op)?.not_undef()?;
         if this.is_null(mutex)? {
             return this.eval_libc_i32("EINVAL");
         }
-        let mutex_place = this.deref_operand(mutex_op)?;
-
-        let i32_layout = this.layout_of(this.tcx.types.i32)?;
 
         let attr = this.read_scalar(attr_op)?.not_undef()?;
         let kind = if this.is_null(attr)? {
             this.eval_libc("PTHREAD_MUTEX_DEFAULT")?
         } else {
-            let attr_place = this.deref_operand(attr_op)?;
-            let attr_kind_place = attr_place.offset(Size::ZERO, MemPlaceMeta::None, i32_layout, this)?;
-            this.read_scalar(attr_kind_place.into())?.not_undef()?
+            mutexattr_get_kind(this, attr_op)?.not_undef()?
         };
 
-        let u32_layout = this.layout_of(this.tcx.types.u32)?;
-        let locked_count_place = mutex_place.offset(Size::from_bytes(4), MemPlaceMeta::None, u32_layout, this)?;
-        this.write_scalar(Scalar::from_u32(0), locked_count_place.into())?;
-
-        let mutex_kind_place = mutex_place.offset(Size::from_bytes(12), MemPlaceMeta::None, i32_layout, &*this.tcx)?;
-        this.write_scalar(kind, mutex_kind_place.into())?;
+        mutex_set_locked_count(this, mutex_op, Scalar::from_u32(0))?;
+        mutex_set_kind(this, mutex_op, kind)?;
 
         Ok(0)
     }
@@ -130,39 +87,30 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn pthread_mutex_lock(&mut self, mutex_op: OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
-        // Ensure that the following reads and writes at offsets to the mutex pointer are within bounds
-        assert_ptr_target_min_size(this, mutex_op, 16)?;
-
         let mutex = this.read_scalar(mutex_op)?.not_undef()?;
         if this.is_null(mutex)? {
             return this.eval_libc_i32("EINVAL");
         }
-        let mutex_place = this.deref_operand(mutex_op)?;
 
-        let i32_layout = this.layout_of(this.tcx.types.i32)?;
-        let kind_place = mutex_place.offset(Size::from_bytes(12), MemPlaceMeta::None, i32_layout, this)?;
-        let kind = this.read_scalar(kind_place.into())?.not_undef()?;
-
-        let u32_layout = this.layout_of(this.tcx.types.u32)?;
-        let locked_count_place = mutex_place.offset(Size::from_bytes(4), MemPlaceMeta::None, u32_layout, this)?;
-        let locked_count = this.read_scalar(locked_count_place.into())?.to_u32()?;
+        let kind = mutex_get_kind(this, mutex_op)?.not_undef()?;
+        let locked_count = mutex_get_locked_count(this, mutex_op)?.to_u32()?;
 
         if kind == this.eval_libc("PTHREAD_MUTEX_NORMAL")? {
             if locked_count == 0 {
-                this.write_scalar(Scalar::from_u32(1), locked_count_place.into())?;
+                mutex_set_locked_count(this, mutex_op, Scalar::from_u32(1))?;
                 Ok(0)
             } else {
                 throw_unsup_format!("Deadlock due to locking a PTHREAD_MUTEX_NORMAL mutex twice");
             }
         } else if kind == this.eval_libc("PTHREAD_MUTEX_ERRORCHECK")? {
             if locked_count == 0 {
-                this.write_scalar(Scalar::from_u32(1), locked_count_place.into())?;
+                mutex_set_locked_count(this, mutex_op, Scalar::from_u32(1))?;
                 Ok(0)
             } else {
                 this.eval_libc_i32("EDEADLK")
             }
         } else if kind == this.eval_libc("PTHREAD_MUTEX_RECURSIVE")? {
-            this.write_scalar(Scalar::from_u32(locked_count + 1), locked_count_place.into())?;
+            mutex_set_locked_count(this, mutex_op, Scalar::from_u32(locked_count + 1))?;
             Ok(0)
         } else {
             this.eval_libc_i32("EINVAL")
@@ -172,33 +120,25 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn pthread_mutex_trylock(&mut self, mutex_op: OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
-        // Ensure that the following reads and writes at offsets to the mutex pointer are within bounds
-        assert_ptr_target_min_size(this, mutex_op, 16)?;
-
         let mutex = this.read_scalar(mutex_op)?.not_undef()?;
         if this.is_null(mutex)? {
             return this.eval_libc_i32("EINVAL");
         }
-        let mutex_place = this.deref_operand(mutex_op)?;
 
-        let i32_layout = this.layout_of(this.tcx.types.i32)?;
-        let kind_place = mutex_place.offset(Size::from_bytes(12), MemPlaceMeta::None, i32_layout, this)?;
-        let kind = this.read_scalar(kind_place.into())?.not_undef()?;
+        let kind = mutex_get_kind(this, mutex_op)?.not_undef()?;
+        let locked_count = mutex_get_locked_count(this, mutex_op)?.to_u32()?;
 
-        let u32_layout = this.layout_of(this.tcx.types.u32)?;
-        let locked_count_place = mutex_place.offset(Size::from_bytes(4), MemPlaceMeta::None, u32_layout, this)?;
-        let locked_count = this.read_scalar(locked_count_place.into())?.to_u32()?;
-
-        if kind == this.eval_libc("PTHREAD_MUTEX_NORMAL")? ||
-                kind == this.eval_libc("PTHREAD_MUTEX_ERRORCHECK")? {
+        if kind == this.eval_libc("PTHREAD_MUTEX_NORMAL")?
+            || kind == this.eval_libc("PTHREAD_MUTEX_ERRORCHECK")?
+        {
             if locked_count == 0 {
-                this.write_scalar(Scalar::from_u32(1), locked_count_place.into())?;
+                mutex_set_locked_count(this, mutex_op, Scalar::from_u32(1))?;
                 Ok(0)
             } else {
                 this.eval_libc_i32("EBUSY")
             }
         } else if kind == this.eval_libc("PTHREAD_MUTEX_RECURSIVE")? {
-            this.write_scalar(Scalar::from_u32(locked_count + 1), locked_count_place.into())?;
+            mutex_set_locked_count(this, mutex_op, Scalar::from_u32(locked_count + 1))?;
             Ok(0)
         } else {
             this.eval_libc_i32("EINVAL")
@@ -208,40 +148,33 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn pthread_mutex_unlock(&mut self, mutex_op: OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
-        // Ensure that the following reads and writes at offsets to the mutex pointer are within bounds
-        assert_ptr_target_min_size(this, mutex_op, 16)?;
-
         let mutex = this.read_scalar(mutex_op)?.not_undef()?;
         if this.is_null(mutex)? {
             return this.eval_libc_i32("EINVAL");
         }
-        let mutex_place = this.deref_operand(mutex_op)?;
 
-        let i32_layout = this.layout_of(this.tcx.types.i32)?;
-        let kind_place = mutex_place.offset(Size::from_bytes(12), MemPlaceMeta::None, i32_layout, this)?;
-        let kind = this.read_scalar(kind_place.into())?.not_undef()?;
-
-        let u32_layout = this.layout_of(this.tcx.types.u32)?;
-        let locked_count_place = mutex_place.offset(Size::from_bytes(4), MemPlaceMeta::None, u32_layout, this)?;
-        let locked_count = this.read_scalar(locked_count_place.into())?.to_u32()?;
+        let kind = mutex_get_kind(this, mutex_op)?.not_undef()?;
+        let locked_count = mutex_get_locked_count(this, mutex_op)?.to_u32()?;
 
         if kind == this.eval_libc("PTHREAD_MUTEX_NORMAL")? {
             if locked_count == 1 {
-                this.write_scalar(Scalar::from_u32(0), locked_count_place.into())?;
+                mutex_set_locked_count(this, mutex_op, Scalar::from_u32(0))?;
                 Ok(0)
             } else {
-                throw_ub_format!("Attempted to unlock a PTHREAD_MUTEX_NORMAL mutex that was not locked");
+                throw_ub_format!(
+                    "Attempted to unlock a PTHREAD_MUTEX_NORMAL mutex that was not locked"
+                );
             }
         } else if kind == this.eval_libc("PTHREAD_MUTEX_ERRORCHECK")? {
             if locked_count == 1 {
-                this.write_scalar(Scalar::from_u32(0), locked_count_place.into())?;
+                mutex_set_locked_count(this, mutex_op, Scalar::from_u32(0))?;
                 Ok(0)
             } else {
                 this.eval_libc_i32("EPERM")
             }
         } else if kind == this.eval_libc("PTHREAD_MUTEX_RECURSIVE")? {
             if locked_count > 0 {
-                this.write_scalar(Scalar::from_u32(locked_count - 1), locked_count_place.into())?;
+                mutex_set_locked_count(this, mutex_op, Scalar::from_u32(locked_count - 1))?;
                 Ok(0)
             } else {
                 this.eval_libc_i32("EPERM")
@@ -254,56 +187,37 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn pthread_mutex_destroy(&mut self, mutex_op: OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
-        // Ensure that the following read and writes at offsets to the mutex pointer are within bounds
-        assert_ptr_target_min_size(this, mutex_op, 16)?;
-
         let mutex = this.read_scalar(mutex_op)?.not_undef()?;
         if this.is_null(mutex)? {
             return this.eval_libc_i32("EINVAL");
         }
-        let mutex_place = this.deref_operand(mutex_op)?;
 
-        let u32_layout = this.layout_of(this.tcx.types.u32)?;
-        let locked_count_place = mutex_place.offset(Size::from_bytes(4), MemPlaceMeta::None, u32_layout, this)?;
-        if this.read_scalar(locked_count_place.into())?.to_u32()? != 0 {
+        if mutex_get_locked_count(this, mutex_op)?.to_u32()? != 0 {
             return this.eval_libc_i32("EBUSY");
         }
 
-        let i32_layout = this.layout_of(this.tcx.types.i32)?;
-        let kind_place = mutex_place.offset(Size::from_bytes(12), MemPlaceMeta::None, i32_layout, this)?;
-        this.write_scalar(ScalarMaybeUndef::Undef, kind_place.into())?;
-        this.write_scalar(ScalarMaybeUndef::Undef, locked_count_place.into())?;
+        mutex_set_kind(this, mutex_op, ScalarMaybeUndef::Undef)?;
+        mutex_set_locked_count(this, mutex_op, ScalarMaybeUndef::Undef)?;
 
         Ok(0)
     }
 
-    // pthread_rwlock_t is between 32 and 56 bytes, depending on the platform
-    // memory layout:
-    // bytes 0-3: reserved for signature on macOS
-    // bytes 4-7: reader count, as a u32
-    // bytes 8-11: writer count, as a u32
-
     fn pthread_rwlock_rdlock(&mut self, rwlock_op: OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
-        // Ensure that the following reads and write at offsets to the rwlock pointer are within bounds
-        assert_ptr_target_min_size(this, rwlock_op, 12)?;
-
         let rwlock = this.read_scalar(rwlock_op)?.not_undef()?;
         if this.is_null(rwlock)? {
             return this.eval_libc_i32("EINVAL");
         }
-        let rwlock_place = this.deref_operand(rwlock_op)?;
 
-        let u32_layout = this.layout_of(this.tcx.types.u32)?;
-        let readers_place = rwlock_place.offset(Size::from_bytes(4), MemPlaceMeta::None, u32_layout, this)?;
-        let writers_place = rwlock_place.offset(Size::from_bytes(8), MemPlaceMeta::None, u32_layout, this)?;
-        let readers = this.read_scalar(readers_place.into())?.to_u32()?;
-        let writers = this.read_scalar(writers_place.into())?.to_u32()?;
+        let readers = rwlock_get_readers(this, rwlock_op)?.to_u32()?;
+        let writers = rwlock_get_writers(this, rwlock_op)?.to_u32()?;
         if writers != 0 {
-            throw_unsup_format!("Deadlock due to read-locking a pthreads read-write lock while it is already write-locked");
+            throw_unsup_format!(
+                "Deadlock due to read-locking a pthreads read-write lock while it is already write-locked"
+            );
         } else {
-            this.write_scalar(Scalar::from_u32(readers + 1), readers_place.into())?;
+            rwlock_set_readers(this, rwlock_op, Scalar::from_u32(readers + 1))?;
             Ok(0)
         }
     }
@@ -311,24 +225,17 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn pthread_rwlock_tryrdlock(&mut self, rwlock_op: OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
-        // Ensure that the following reads and write at offsets to the rwlock pointer are within bounds
-        assert_ptr_target_min_size(this, rwlock_op, 12)?;
-
         let rwlock = this.read_scalar(rwlock_op)?.not_undef()?;
         if this.is_null(rwlock)? {
             return this.eval_libc_i32("EINVAL");
         }
-        let rwlock_place = this.deref_operand(rwlock_op)?;
 
-        let u32_layout = this.layout_of(this.tcx.types.u32)?;
-        let readers_place = rwlock_place.offset(Size::from_bytes(4), MemPlaceMeta::None, u32_layout, this)?;
-        let writers_place = rwlock_place.offset(Size::from_bytes(8), MemPlaceMeta::None, u32_layout, this)?;
-        let readers = this.read_scalar(readers_place.into())?.to_u32()?;
-        let writers = this.read_scalar(writers_place.into())?.to_u32()?;
+        let readers = rwlock_get_readers(this, rwlock_op)?.to_u32()?;
+        let writers = rwlock_get_writers(this, rwlock_op)?.to_u32()?;
         if writers != 0 {
             this.eval_libc_i32("EBUSY")
         } else {
-            this.write_scalar(Scalar::from_u32(readers + 1), readers_place.into())?;
+            rwlock_set_readers(this, rwlock_op, Scalar::from_u32(readers + 1))?;
             Ok(0)
         }
     }
@@ -336,26 +243,23 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn pthread_rwlock_wrlock(&mut self, rwlock_op: OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
-        // Ensure that the following reads and write at offsets to the rwlock pointer are within bounds
-        assert_ptr_target_min_size(this, rwlock_op, 12)?;
-
         let rwlock = this.read_scalar(rwlock_op)?.not_undef()?;
         if this.is_null(rwlock)? {
             return this.eval_libc_i32("EINVAL");
         }
-        let rwlock_place = this.deref_operand(rwlock_op)?;
 
-        let u32_layout = this.layout_of(this.tcx.types.u32)?;
-        let readers_place = rwlock_place.offset(Size::from_bytes(4), MemPlaceMeta::None, u32_layout, this)?;
-        let writers_place = rwlock_place.offset(Size::from_bytes(8), MemPlaceMeta::None, u32_layout, this)?;
-        let readers = this.read_scalar(readers_place.into())?.to_u32()?;
-        let writers = this.read_scalar(writers_place.into())?.to_u32()?;
+        let readers = rwlock_get_readers(this, rwlock_op)?.to_u32()?;
+        let writers = rwlock_get_writers(this, rwlock_op)?.to_u32()?;
         if readers != 0 {
-            throw_unsup_format!("Deadlock due to write-locking a pthreads read-write lock while it is already read-locked");
+            throw_unsup_format!(
+                "Deadlock due to write-locking a pthreads read-write lock while it is already read-locked"
+            );
         } else if writers != 0 {
-            throw_unsup_format!("Deadlock due to write-locking a pthreads read-write lock while it is already write-locked");
+            throw_unsup_format!(
+                "Deadlock due to write-locking a pthreads read-write lock while it is already write-locked"
+            );
         } else {
-            this.write_scalar(Scalar::from_u32(1), writers_place.into())?;
+            rwlock_set_writers(this, rwlock_op, Scalar::from_u32(1))?;
             Ok(0)
         }
     }
@@ -363,24 +267,17 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn pthread_rwlock_trywrlock(&mut self, rwlock_op: OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
-        // Ensure that the following reads and write at offsets to the rwlock pointer are within bounds
-        assert_ptr_target_min_size(this, rwlock_op, 12)?;
-
         let rwlock = this.read_scalar(rwlock_op)?.not_undef()?;
         if this.is_null(rwlock)? {
             return this.eval_libc_i32("EINVAL");
         }
-        let rwlock_place = this.deref_operand(rwlock_op)?;
 
-        let u32_layout = this.layout_of(this.tcx.types.u32)?;
-        let readers_place = rwlock_place.offset(Size::from_bytes(4), MemPlaceMeta::None, u32_layout, this)?;
-        let writers_place = rwlock_place.offset(Size::from_bytes(8), MemPlaceMeta::None, u32_layout, this)?;
-        let readers = this.read_scalar(readers_place.into())?.to_u32()?;
-        let writers = this.read_scalar(writers_place.into())?.to_u32()?;
+        let readers = rwlock_get_readers(this, rwlock_op)?.to_u32()?;
+        let writers = rwlock_get_writers(this, rwlock_op)?.to_u32()?;
         if readers != 0 || writers != 0 {
             this.eval_libc_i32("EBUSY")
         } else {
-            this.write_scalar(Scalar::from_u32(1), writers_place.into())?;
+            rwlock_set_writers(this, rwlock_op, Scalar::from_u32(1))?;
             Ok(0)
         }
     }
@@ -388,25 +285,18 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn pthread_rwlock_unlock(&mut self, rwlock_op: OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
-        // Ensure that the following reads and writes at offsets to the rwlock pointer are within bounds
-        assert_ptr_target_min_size(this, rwlock_op, 12)?;
-
         let rwlock = this.read_scalar(rwlock_op)?.not_undef()?;
         if this.is_null(rwlock)? {
             return this.eval_libc_i32("EINVAL");
         }
-        let rwlock_place = this.deref_operand(rwlock_op)?;
 
-        let u32_layout = this.layout_of(this.tcx.types.u32)?;
-        let readers_place = rwlock_place.offset(Size::from_bytes(4), MemPlaceMeta::None, u32_layout, this)?;
-        let writers_place = rwlock_place.offset(Size::from_bytes(8), MemPlaceMeta::None, u32_layout, this)?;
-        let readers = this.read_scalar(readers_place.into())?.to_u32()?;
-        let writers = this.read_scalar(writers_place.into())?.to_u32()?;
+        let readers = rwlock_get_readers(this, rwlock_op)?.to_u32()?;
+        let writers = rwlock_get_writers(this, rwlock_op)?.to_u32()?;
         if readers != 0 {
-            this.write_scalar(Scalar::from_u32(readers - 1), readers_place.into())?;
+            rwlock_set_readers(this, rwlock_op, Scalar::from_u32(readers - 1))?;
             Ok(0)
         } else if writers != 0 {
-            this.write_scalar(Scalar::from_u32(0), writers_place.into())?;
+            rwlock_set_writers(this, rwlock_op, Scalar::from_u32(0))?;
             Ok(0)
         } else {
             this.eval_libc_i32("EPERM")
@@ -416,38 +306,186 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn pthread_rwlock_destroy(&mut self, rwlock_op: OpTy<'tcx, Tag>) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
-        // Ensure that the following reads and writes at offsets to the rwlock pointer are within bounds
-        assert_ptr_target_min_size(this, rwlock_op, 12)?;
-
         let rwlock = this.read_scalar(rwlock_op)?.not_undef()?;
         if this.is_null(rwlock)? {
             return this.eval_libc_i32("EINVAL");
         }
-        let rwlock_place = this.deref_operand(rwlock_op)?;
 
-        let u32_layout = this.layout_of(this.tcx.types.u32)?;
-        let readers_place = rwlock_place.offset(Size::from_bytes(4), MemPlaceMeta::None, u32_layout, this)?;
-        if this.read_scalar(readers_place.into())?.to_u32()? != 0 {
+        if rwlock_get_readers(this, rwlock_op)?.to_u32()? != 0 {
             return this.eval_libc_i32("EBUSY");
         }
-        let writers_place = rwlock_place.offset(Size::from_bytes(8), MemPlaceMeta::None, u32_layout, this)?;
-        if this.read_scalar(writers_place.into())?.to_u32()? != 0 {
+        if rwlock_get_writers(this, rwlock_op)?.to_u32()? != 0 {
             return this.eval_libc_i32("EBUSY");
         }
 
-        this.write_scalar(ScalarMaybeUndef::Undef, readers_place.into())?;
-        this.write_scalar(ScalarMaybeUndef::Undef, writers_place.into())?;
+        rwlock_set_readers(this, rwlock_op, ScalarMaybeUndef::Undef)?;
+        rwlock_set_writers(this, rwlock_op, ScalarMaybeUndef::Undef)?;
 
         Ok(0)
     }
 }
 
-fn assert_ptr_target_min_size<'mir, 'tcx: 'mir>(ecx: &MiriEvalContext<'mir, 'tcx>, operand: OpTy<'tcx, Tag>, min_size: u64) -> InterpResult<'tcx, ()> {
+fn assert_ptr_target_min_size<'mir, 'tcx: 'mir>(
+    ecx: &MiriEvalContext<'mir, 'tcx>,
+    operand: OpTy<'tcx, Tag>,
+    min_size: u64,
+) -> InterpResult<'tcx, ()> {
     let target_ty = match operand.layout.ty.kind {
-        TyKind::RawPtr(TypeAndMut{ ty, mutbl: _ }) => ty,
+        TyKind::RawPtr(TypeAndMut { ty, mutbl: _ }) => ty,
         _ => panic!("Argument to pthread function was not a raw pointer"),
     };
     let target_layout = ecx.layout_of(target_ty)?;
     assert!(target_layout.size.bytes() >= min_size);
     Ok(())
 }
+
+// pthread_mutexattr_t is either 4 or 8 bytes, depending on the platform
+// memory layout: store an i32 in the first four bytes equal to the
+// corresponding libc mutex kind constant (i.e. PTHREAD_MUTEX_NORMAL)
+
+fn mutexattr_get_kind<'mir, 'tcx: 'mir>(
+    ecx: &MiriEvalContext<'mir, 'tcx>,
+    attr_op: OpTy<'tcx, Tag>,
+) -> InterpResult<'tcx, ScalarMaybeUndef<Tag>> {
+    // Ensure that the following read at an offset to the attr pointer is within bounds
+    assert_ptr_target_min_size(ecx, attr_op, 4)?;
+    let attr_place = ecx.deref_operand(attr_op)?;
+    let i32_layout = ecx.layout_of(ecx.tcx.types.i32)?;
+    let kind_place = attr_place.offset(Size::ZERO, MemPlaceMeta::None, i32_layout, ecx)?;
+    ecx.read_scalar(kind_place.into())
+}
+
+fn mutexattr_set_kind<'mir, 'tcx: 'mir>(
+    ecx: &mut MiriEvalContext<'mir, 'tcx>,
+    attr_op: OpTy<'tcx, Tag>,
+    kind: impl Into<ScalarMaybeUndef<Tag>>,
+) -> InterpResult<'tcx, ()> {
+    // Ensure that the following write at an offset to the attr pointer is within bounds
+    assert_ptr_target_min_size(ecx, attr_op, 4)?;
+    let attr_place = ecx.deref_operand(attr_op)?;
+    let i32_layout = ecx.layout_of(ecx.tcx.types.i32)?;
+    let kind_place = attr_place.offset(Size::ZERO, MemPlaceMeta::None, i32_layout, ecx)?;
+    ecx.write_scalar(kind.into(), kind_place.into())
+}
+
+// pthread_mutex_t is between 24 and 48 bytes, depending on the platform
+// memory layout:
+// bytes 0-3: reserved for signature on macOS
+// bytes 4-7: count of how many times this mutex has been locked, as a u32
+// bytes 12-15: mutex kind, as an i32
+// (the kind should be at this offset for compatibility with the static
+// initializer macro)
+
+fn mutex_get_locked_count<'mir, 'tcx: 'mir>(
+    ecx: &MiriEvalContext<'mir, 'tcx>,
+    mutex_op: OpTy<'tcx, Tag>,
+) -> InterpResult<'tcx, ScalarMaybeUndef<Tag>> {
+    // Ensure that the following read at an offset to the mutex pointer is within bounds
+    assert_ptr_target_min_size(ecx, mutex_op, 16)?;
+    let mutex_place = ecx.deref_operand(mutex_op)?;
+    let u32_layout = ecx.layout_of(ecx.tcx.types.u32)?;
+    let locked_count_place =
+        mutex_place.offset(Size::from_bytes(4), MemPlaceMeta::None, u32_layout, ecx)?;
+    ecx.read_scalar(locked_count_place.into())
+}
+
+fn mutex_set_locked_count<'mir, 'tcx: 'mir>(
+    ecx: &mut MiriEvalContext<'mir, 'tcx>,
+    mutex_op: OpTy<'tcx, Tag>,
+    locked_count: impl Into<ScalarMaybeUndef<Tag>>,
+) -> InterpResult<'tcx, ()> {
+    // Ensure that the following write at an offset to the mutex pointer is within bounds
+    assert_ptr_target_min_size(ecx, mutex_op, 16)?;
+    let mutex_place = ecx.deref_operand(mutex_op)?;
+    let u32_layout = ecx.layout_of(ecx.tcx.types.u32)?;
+    let locked_count_place =
+        mutex_place.offset(Size::from_bytes(4), MemPlaceMeta::None, u32_layout, ecx)?;
+    ecx.write_scalar(locked_count.into(), locked_count_place.into())
+}
+
+fn mutex_get_kind<'mir, 'tcx: 'mir>(
+    ecx: &MiriEvalContext<'mir, 'tcx>,
+    mutex_op: OpTy<'tcx, Tag>,
+) -> InterpResult<'tcx, ScalarMaybeUndef<Tag>> {
+    // Ensure that the following read at an offset to the mutex pointer is within bounds
+    assert_ptr_target_min_size(ecx, mutex_op, 16)?;
+    let mutex_place = ecx.deref_operand(mutex_op)?;
+    let i32_layout = ecx.layout_of(ecx.tcx.types.i32)?;
+    let kind_place =
+        mutex_place.offset(Size::from_bytes(12), MemPlaceMeta::None, i32_layout, ecx)?;
+    ecx.read_scalar(kind_place.into())
+}
+
+fn mutex_set_kind<'mir, 'tcx: 'mir>(
+    ecx: &mut MiriEvalContext<'mir, 'tcx>,
+    mutex_op: OpTy<'tcx, Tag>,
+    kind: impl Into<ScalarMaybeUndef<Tag>>,
+) -> InterpResult<'tcx, ()> {
+    // Ensure that the following write at an offset to the mutex pointer is within bounds
+    assert_ptr_target_min_size(ecx, mutex_op, 16)?;
+    let mutex_place = ecx.deref_operand(mutex_op)?;
+    let i32_layout = ecx.layout_of(ecx.tcx.types.i32)?;
+    let kind_place =
+        mutex_place.offset(Size::from_bytes(12), MemPlaceMeta::None, i32_layout, ecx)?;
+    ecx.write_scalar(kind.into(), kind_place.into())
+}
+
+// pthread_rwlock_t is between 32 and 56 bytes, depending on the platform
+// memory layout:
+// bytes 0-3: reserved for signature on macOS
+// bytes 4-7: reader count, as a u32
+// bytes 8-11: writer count, as a u32
+
+fn rwlock_get_readers<'mir, 'tcx: 'mir>(
+    ecx: &MiriEvalContext<'mir, 'tcx>,
+    rwlock_op: OpTy<'tcx, Tag>,
+) -> InterpResult<'tcx, ScalarMaybeUndef<Tag>> {
+    // Ensure that the following read at an offset to the rwlock pointer is within bounds
+    assert_ptr_target_min_size(ecx, rwlock_op, 12)?;
+    let rwlock_place = ecx.deref_operand(rwlock_op)?;
+    let u32_layout = ecx.layout_of(ecx.tcx.types.u32)?;
+    let readers_place =
+        rwlock_place.offset(Size::from_bytes(4), MemPlaceMeta::None, u32_layout, ecx)?;
+    ecx.read_scalar(readers_place.into())
+}
+
+fn rwlock_set_readers<'mir, 'tcx: 'mir>(
+    ecx: &mut MiriEvalContext<'mir, 'tcx>,
+    rwlock_op: OpTy<'tcx, Tag>,
+    readers: impl Into<ScalarMaybeUndef<Tag>>,
+) -> InterpResult<'tcx, ()> {
+    // Ensure that the following write at an offset to the rwlock pointer is within bounds
+    assert_ptr_target_min_size(ecx, rwlock_op, 12)?;
+    let rwlock_place = ecx.deref_operand(rwlock_op)?;
+    let u32_layout = ecx.layout_of(ecx.tcx.types.u32)?;
+    let readers_place =
+        rwlock_place.offset(Size::from_bytes(4), MemPlaceMeta::None, u32_layout, ecx)?;
+    ecx.write_scalar(readers.into(), readers_place.into())
+}
+
+fn rwlock_get_writers<'mir, 'tcx: 'mir>(
+    ecx: &MiriEvalContext<'mir, 'tcx>,
+    rwlock_op: OpTy<'tcx, Tag>,
+) -> InterpResult<'tcx, ScalarMaybeUndef<Tag>> {
+    // Ensure that the following read at an offset to the rwlock pointer is within bounds
+    assert_ptr_target_min_size(ecx, rwlock_op, 12)?;
+    let rwlock_place = ecx.deref_operand(rwlock_op)?;
+    let u32_layout = ecx.layout_of(ecx.tcx.types.u32)?;
+    let writers_place =
+        rwlock_place.offset(Size::from_bytes(8), MemPlaceMeta::None, u32_layout, ecx)?;
+    ecx.read_scalar(writers_place.into())
+}
+
+fn rwlock_set_writers<'mir, 'tcx: 'mir>(
+    ecx: &mut MiriEvalContext<'mir, 'tcx>,
+    rwlock_op: OpTy<'tcx, Tag>,
+    writers: impl Into<ScalarMaybeUndef<Tag>>,
+) -> InterpResult<'tcx, ()> {
+    // Ensure that the following write at an offset to the rwlock pointer is within bounds
+    assert_ptr_target_min_size(ecx, rwlock_op, 12)?;
+    let rwlock_place = ecx.deref_operand(rwlock_op)?;
+    let u32_layout = ecx.layout_of(ecx.tcx.types.u32)?;
+    let writers_place =
+        rwlock_place.offset(Size::from_bytes(8), MemPlaceMeta::None, u32_layout, ecx)?;
+    ecx.write_scalar(writers.into(), writers_place.into())
+}